What is the ruling on the actions of a mother who quarrels with her husband, abuses him, accuses him of gambling, hates her son and invokes curses upon him and his children, and favors her married daughters over her other daughter?

If a mother mistreats her husband and falsely accuses him, she is committing a forbidden act. Similarly, her supplication against her children without just cause is impermissible and falls under transgression in supplication. She must also be just among her children. However, the right of the mother is immense, and honoring her is one of the reasons for Allah's pleasure. Her right to dutifulness does not diminish, no matter her condition. Therefore, it is obligatory to consistently honor her and treat her kindly, and to be careful not to sever ties with her. There is no harm in gently advising her, or seeking assistance from someone who can advise her, and frequently supplicating for her. If you fulfill your duty of honoring her, then her anger towards you or her dislike of you will not harm you.