What is the right of the husband’s mother over her son’s wife in Islamic law, and what is the sin of a wife who disobeys her husband by refusing to help his mother, and will the wife be held accountable if she severs ties with her family for this reason?

A wife's assistance to her husband's mother in cooking matters is commendable and praiseworthy, and it indicates her virtue and eagerness to do good. It falls under the category of a Muslim helping his brother, and the husband's mother is the most deserving of this help. It also entails obedience to the husband and gaining his affection. However, it is not obligatory for the wife to do so, and it is not permissible for the husband to boycott her family because of her refusal to help.