Do Animals Go to Jannah?
Question

Recently my 20 year old cat died and my young nieces asked whether animals would go to Heaven and I really could not answer them since I don't know the answer myself. 
Do they go to Heaven/Hell and how can we make amends if we were cruel to the animals (especially since they have since died)?
Praise be to Allah.Do animals go to Jannah?
Allah says (interpretation of the meaning): 
“And when the wild beasts shall be gathered together.” [al-Takwir 81:5] 
“There is not a moving (living) creature on earth, nor a bird that flies with its two wings, but are communities like you. We have neglected nothing in the Book, then unto their Lord they (all) shall be gathered.” [al-An'am 6:38] 
Ibn 'Abbas said: “Everything will be gathered , even the flies.” 
On the Day of Resurrection, the animals will settle scores between one another . It says in a hadith of Abu Hurayrah that the Messenger of Allah (peace and blessings of Allah be upon him) said: “All scores will be settled on the Day of Resurrection; even the hornless sheep will settle its scores with the horned sheep.” (Narrated by Muslim, al-Birr wa’l-Silah wa’l-Adab, 4679)
It says in another hadith: “Allah will judge between His creation, jinn, humans and animals. On that Day the score will be settled between the hornless and the horned, until there are no outstanding issues left, then Allah will say, ‘Be dust!’ At that point the kafir will say, ‘Would that I were dust!’” Shaykh al-Albani said: (This is sahih. No. 1966; see al-Silsilah al-Sahihah, part 4, p. 966)
What does Islam say about caring for animals?
What is obligatory for the Muslim is to be kind to animals and not harm or annoy them. It was reported that a woman was punished because of a cat. Al-Bukhari narrated from Ibn ‘Umar (may Allah be pleased with them both) that the Prophet (peace and blessings of Allaah be upon him) said: “A woman went to Hell because of a cat which she tied up, and did not feed it or let it eat of the vermin of the earth.” (Bad al-Khalq, 3071) 
And Allah forgave a prostitute because she was kind to a dog. Al-Bukhari also narrated that Abu Hurayrah (may Allah be pleased with him) said: “The Messenger of Allah (peace and blessings of Allah be upon him) said: ‘Whilst a dog was walking around a well, almost dying of thirst, one of the prostitutes of Bani Israil saw him, took off her shoe and gave him water. She was forgiven because of that.” (Ahadith al-Anbiya, 3208) 
Whoever harms an animal has to repent to Allah for that, because the Lord of the animals is the One Who has commanded us to be kind towards them (unless they are harmful)