She respects her mother-in-law more than she respects her mother!
Question

                Will I be rewarded for honouring my mother-in-law? 

Will Allaah forgive me for not respecting my mother as I should, if I respect my mother-in-law?.
Praise be to Allah.
    Allaah has prescribed the best and most just of rulings, 
    which bring happiness to individuals, families and societies. Hence He has 
    prescribed rights and duties for every individual in society, so life will 
    run smoothly and each person will know what he is entitled to and what he 
    must do. 

    The husband’s rights over his wife are great, and have to do 
    with him, his wealth, his house and his family. Showing respect to the 
    husband’s family, especially his parents, is part of showing respect to 
    one’s husband and treating him well. When a woman does her duties towards 
    her husband, she is obeying her Lord and has the hope of reward from Him.  

    Honouring your mother-in-law is something that is to be 
    appreciated, and no one can deny that. Rather what you are doing is in 
    accordance with Islam and common sense. By doing that you are earning the 
    pleasure of your husband and contributing to the success of your marriage 
    and protecting it against things that may spoil it.   

    But one should not obey one's Lord in one way and forget 
    other aspects. It is not permissible for your respect towards your 
    mother-in-law to be at the expense of respect for your own mother, because 
    parents – and especially the mother – have important rights over their 
    children. See the answer to question no. 
    5053 for more information on the 
    mother’s rights over her children. 

    You have to honour your mother and treat her kindly even if 
    she is a kaafir, as much as you can and as much as your circumstances allow. 
    But if she calls you to kufr and strives to make you follow that, as our 
    Lord says (interpretation of the meaning):  

    “And We have enjoined on man to be good and dutiful to his 
    parents; but if they strive to make you join with Me (in worship) anything 
    (as a partner) of which you have no knowledge, then obey them not” 
    

    [al-‘Ankaboot 29:8] 

    and  

    “But if they (both) strive with you to make you join in 
    worship with Me others that of which you have no knowledge, then obey them 
    not; but behave with them in the world kindly” 

    [Luqmaan 31:15].  

    So what are her rights over you if she is a Muslim who 
    believes in the Oneness of Allaah (Tawheed)? 

    It was narrated that Asma’ bint ‘Abi Bakr (may Allaah be 
    pleased with her) said: My mother came to visit me when she was a mushrikah, 
    at the time of the Messenger of Allaah  (peace and blessings of Allaah 
    be upon him). I consulted the Messenger of Allaah  (peace and blessings 
    of Allaah be upon him) and said: She is expecting (something), should I 
    uphold the ties of kinship with my mother? He said: “Yes, uphold the ties of 
    kinship with your mother.”  

    Narrated by al-Bukhaari (2477) and Muslim (1003). 

    What is meant by expecting something is that she wants her 
    daughter to honour her. 

    So do two good things at the same time: honour your mother 
    and your mother-in-law. If there is a conflict between the two, then do not 
    give your mother-in-law or any other woman precedence over your mother, so 
    long as that will not cause any trouble between you and your husband. 

    We ask Allaah to help you to do that which pleases Him and to 
    make you among the woman who are righteous and devout. 

    See also the answer to question no. 
    22782 and 
    5326. 

    And Allaah knows best.