Consoling a parent for the loss of a daughter
Question

My 16 year old daughter past away last October in the month of Shaaban from Cancer in her stomach. She was a good muslim that always prayed and seeked islamic knowlege. Is their anything I can do in the month of Ramadan that would increase her rewards? How can I deal with her loss. Please help?.
Praise be to Allah.I ask Allah, may He be exalted, by His names and attributes, to encompass your daughter in the vastness of His mercy and to join you with her on the Day of Resurrection in His Paradise, and to grant you and her mother patience and consolation. 
Accept the glad tidings of the words of the Prophet (peace and blessings of Allah be upon him): “Whoever dies of a stomach disease will not be punished in his grave.” Narrated and classed as hasan by al-Tirmidhi (1064); classed as saheeh by al-Albaani in Ahkaam al-Janaa’iz (53). And the Prophet (peace and blessings of Allah be upon him) said: “Whoever dies of a stomach disease is a shaheed (martyr).” Narrated by Muslim (1915). Ibn al-Atheer said: i.e., the one who dies of a stomach disease such as dropsy and the like. Al-Nihaayah, 1/136. We hope that your daughter has attained that by the grace and mercy of Allah. 
Try not to despair at her loss, and hope for goodness for her and reward from Allah. You should think and ponder and study the word of Allah and the Sunnah of His Prophet Muhammad (peace and blessings of Allah be upon him), for therein you will find comfort and peace of mind which will bring tranquillity and ease to those hope for the great reward which Allah bestows upon the one who is patient, accepts (Allah’s decree) and seeks reward. If the one who is faced with calamity compares what has been taken from him with what he has been given of reward, he will find that what he has been given of reward is far, far greater than that which he has lost. All of that is in accordance with His wisdom.  
Allah says (interpretation of the meaning): 
“And certainly, We shall test you with something of fear, hunger, loss of wealth, lives and fruits, but give glad tidings to As‑ Saabiroon (the patient).
156. Who, when afflicted with calamity, say: “Truly, to Allah we belong and truly, to Him we shall return.”
157. They are those on whom are the Salawaat (i.e. who are blessed and will be forgiven) from their Lord, and (they are those who) receive His Mercy, and it is they who are the guided ones”
[al-Baqarah 2:155-157]
Muslim narrated in his Saheeh (917) that Umm Salamah (may Allah be pleased with her) said: I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: “There is no person who is afflicted with a calamity and says, ‘Verily to Allah we belong and unto Him is our return. O Allah, reward me for my affliction and compensate me with something better’ – but Allah will reward him for his affliction and compensate him with something better.” She said: When Abu Salamah died, I said: Who is better than Abu Salamah, the companion of the Messenger of Allah (peace and blessings of Allah be upon him)? Then Allah caused me to say it and I said it. She said: Then I married the Messenger of Allah (peace and blessings of Allah be upon him). 
We also present to you these following words of the Prophet (peace and blessings of Allah be upon him) to console the one who has sent on one of his children before him, whose child died during his lifetime, and to give him the glad tidings of the mercy of Allah and His favour upon him. May Allah encompass us and you therein, and bestow His pardon and forgiveness upon us. 
Al-Tirmidhi (2399) narrated and classed as hasan: “Calamity will continue to befall the believer, male of female in himself, his child and his wealth, until he meets Allah with no sin on him.” Classed as saheeh by al-Albaani in Saheeh al-Jaami’, no. 5815. 
It is narrated in the hadeeth that the Messenger of Allah (peace and blessings of Allah be upon him) said: “When a man’s child dies, Allah, may He be exalted, says to His angels: ‘Have you taken the soul of the child of My slave?’ They say, ‘Yes.’ He says, although He knows best, ‘Have you taken the apple of his eye?’ They say, ‘Yes.’ He says: ‘What did My slave say?” They say: ‘He praised You and said Inna Lillaahi wa inna ilayhi raaji’oon (Verily to Allah we belong and unto Him is our return).’ Allah, may He be glorified and exalted, says: ‘Build a house for My slave in Paradise and call it the house of praise.’” Narrated and classed as hasan by al-Tirmidhi (1021); classed as hasan by al-Albaani in al-Silsilah al-Saheehah. 
These are glad tidings that he would die in faith, because if Allah commands that a house be built for one of His slaves, that slave must be going to live in that house one day… Imam Ahmad (3/436) narrated from the hadeeth of Mu’aawiyah ibn Qurrah from his father, which al-Haakim (1/541) classed as saheeh, that a man came to the Prophet (peace and blessings of Allah be upon him) and he had a son of his with him. The Prophet (peace and blessings of Allah be upon him) said: “Do you love him?” He said: “O Messenger of Allah, may Allah love you as I love him.” Then the Prophet (peace and blessings of Allah be upon him) noticed that he was missing and he said: “What happened to the son of So and so?” They said: “O Messenger of Allah, he has died.” The Messenger of Allah (peace and blessings of Allah be upon him) said to his father: “Would you not like to come to one of the gates of Paradise and find him there waiting for you?” The man said: “O Messenger of Allah, is it just for me or for all of us?” He (peace and blessings of Allah be upon him) said: “No, it is for all of you.” Classed as saheeh by al-Albaani in Saheeh al-Targheeb wa’l-Tarheeb, no. 1756. 
With regard to what you can do for your daughter, there are several things:
1 – Sincerely praying (du’aa’) for mercy and forgiveness. It was narrated that Abu’l-Darda’ said: The Messenger of Allah (peace and blessings of Allah be upon him) said: “There is no Muslim who prays for his brother in his absence but the angel says: And you shall have likewise.” Narrated by Muslim, 2732. 
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: The best that one can do for the deceased is say du’aa’. (Liqa’ al-baab il-Maftooh, 1/205) 
2 – Give charity on her behalf, especially ongoing charity (sadaqah jaariyah). Al-Nawawi said: Charity reaches the deceased and he benefits from it, and there is no difference of opinion among the Muslims concerning that. (Sharh al-Nawawi ‘ala Saheeh Muslim, vol. 1, p. 89).
 There is no saheeh evidence that charity given in Ramadaan receives a greater reward than at other times, rather what is narrated is that Ibn ‘Abbaas said: The Messenger of Allah (peace and blessings of Allah be upon him) was the most generous of people and he was at his most generous in Ramadaan, when Jibreel met with him. He would meet with him every night in Ramadaan and review the Qur’aan with him. And the Messenger of Allah (peace and blessings of Allah be upon him) was generous like the wind in doing good. Al-Bukhaari (6), Muslim (2308). 
Al-Nawawi said: This hadeeth teaches us several things, one of which is how generous the Prophet (peace and blessings of Allah be upon him) was, and that it is mustahabb to be generous in Ramadaan. End quote. Sharh al-Nawawi ‘ala Saheeh Muslim, vol. 15, p. 69. 
From the book Fadl man maata lahu min al-Awlaad by al-Suyooti and a lecture entitled Kashf al-Kurbah by Shaykh ‘Ali al-Qarani, and the book Ahkaam al-Janaa’iz by al-Albaani. 
See also question no. 21434.