How should a wife deal with her husband's mother's frequent and financially burdensome demands exclusively on her son, knowing their need for money, and the mother's pity for her other children but not for her son, while the wife fears that she will not be honored in the future?

The mother's right is immense, and no matter what the son does, he can never repay her fully. Allah has specifically enjoined good treatment of her, and the Prophet (peace be upon him) enjoined it three times before mentioning the father. The son must strive to be dutiful to his mother and treat her kindly, fulfilling her needs to the best of his ability, even if she is self-sufficient. The wife should not object to this as long as the husband is providing for her and their children. It must be noted that parents are not permitted to take from their son's wealth in a way that harms him.