All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If your mother deals with you and your father in the way you described, you should, first of all, advise her and direct her to the proper way of dealing with your father (i.e. her husband). Besides, she should not make her child be in dissension with her in such a way that would eventually lead him to be undutiful to her. As for you, we advise you to supplicate Allah much to set your mother's affairs right and guide her to deal well with you, since supplication is one of the best ways to realize the believers’ desires. Allah, the Exalted, says (what means): {And your Lord says, 'Call upon Me; I will respond to you.' Indeed, those who disdain My worship will enter Hell [rendered] contemptible.} [Quran 40:60) You can also seek the help of those people to whom your mother might respond positively, so that Allah might bring about her righteousness due to their advice.
As for your advice to her, it is recommended as long as it is within the limits of the manners laid down by the Sharee'ah, for one is allowed to give advice to his parents in the same way he is allowed to give advice to others; however, he should be more cautious while doing so. In case she positively responds to the advice, you have thus – praise be to Allah – achieved your goal; otherwise, you should keep away from doing so. In his Al-Adaab Ash-Shar