Her mother is rejecting the fiancé because there was no prior relationship or dating
Question

                I am a convert to Islam. Recently, a friend of mine (muslim) found a potential husband for me. I want to do everything Islamically, but my mother equates this with what she calls "marrying a stranger" because there is no dating involved. I want to go ahead with the marriage, but my mother wants me to obey her and not marry the man. I am 27, and am ready to be married. Do I have to obey my mother?.
Praise be to Allah.
    Firstly: 

    We congratulate our sister on embracing Islam and we ask 
    Allah to bless you with the guidance of your family and loved ones, and to 
    help you to obey Him and seek His pleasure, and bless you with a righteous 
    husband and righteous offspring. 

    Secondly: 

    Marriage in Islam is based on the proposal then the marriage 
    contract. For the purposes of the proposal the man is allowed to see the 
    woman and she is allowed to see him, so that the marriage will be based on 
    clarity. That should be accompanied by asking about the man in order to find 
    out about his character, religious commitment and condition, and the 
    situation of his family. If he is good, then the basic principle is that he 
    should be accepted, because the Prophet (blessings and peace of Allah be 
    upon him) said: “If there comes to you one whose 
    religious commitment and attitude pleases you, then marry [your 
    female relative who is under your care] 
    to him, for if you do not do that, there will be tribulation on earth and 
    much corruption.”

    Narrated by at-Tirmidhi (1084) 
    from the hadeeth of Abu Hurayrah. Classed as hasan by al-Albaani in 
    Saheeh at-Tirmidhi. 

    The fiancé is still a stranger to 
    the woman, so it is not permissible for him to be alone with her, or to 
    shake hands with her, or to look at her apart from looking in order to 
    decide whether to go ahead with the proposal. 

    From this you will understand that 
    Islam does not permit a relationship between a man and a woman who is not 
    his mahram, even if that is for the purpose of marriage. This relationship 
    is not permissible either before or after the proposal. But if there is a 
    need to sit with the one who is proposing once or more in order to find out 
    about his situation or to make arrangements for the marriage contract, there 
    is nothing wrong with that so long as a mahram is present, and the woman 
    wears proper hijab, and she treats him as as a man who is a non-mahram.

    Thirdly: 

    If your mother does not approve of 
    the man for the reasons mentioned, which is that she thinks it is essential 
    for there to be dating and a relationship and getting to know one another 
    before proposing marriage, you do not have to obey her in her rejection of 
    this man, because she is calling you to do something that is not permissible 
    in Islam, and there is no obedience to any created being if it involves 
    disobedience to the Creator. In that case you have to explain to her the 
    ruling on these relationships and try to convince her of the marriage by 
    telling her about some of the good qualities of the man after you have asked 
    about him and found out about him. 

    If her rejection is for an 
    acceptable reason, whether it has to do with religious or worldly matters, 
    such as any shortcoming in his wealth or appearance, or something bad in his 
    family and so on, then it is better to obey your moher. 

    If there is no acceptable reason 
    for her refusal, then you do not have to obey her, but you should strive to 
    please her and make her happy because of the great rights to kind treatment 
    and respect that the mother has. 

    Fourthly: 

    In order for the marriage contract 
    to be valid it must done by the woman’s guardian, because the Prophet 
    (blessings and peace of Allah be upon him) said: 
    “There is no marriage except with a guardian.” Narrated by 
    Abu Dawood, 2085; al-Tirmidhi, 1101; Ibn Maajah, 1881, from Abu Moosa 
    al-Ash‘ari. Classed as saheeh by al-Albaani in Saheeh at-Tirmidhi.

    The woman’s guardian is her father, then his father (i.e., 
    paternal grandfather), then her son, then his son (i.e., grandson, if she 
    has a son), then her brother through her father and mother, then her brother 
    through her father only, then their sons, then her paternal uncles, then 
    their sons, then the ruler. See: al-Mughni, 9/355

    If the woman does not have any 
    Muslim guardian from this list, the Muslim judge (qaadi) should do the 
    marriage contract for her. If there is no Muslim judge, then a man of status 
    among the Muslims, such as the Imam of the Islamic Centre, should do the 
    marriage contract for her. 

    We ask Allah, may He be exalted, 
    to help and guide you. 

    And Allah knows best.