What is the ruling of Islamic law on obliging a wife to receive her husband's mother, who has been abusive, and to greet her, despite the mother-in-law's mistreatment of the wife's mother, and the wife's inability to tolerate this situation?

What occurred with the husband's mother is not a justification for the wife to refuse returning to her home and cohabiting with her husband in kindness. Obedience to the husband takes precedence over obedience to parents in this matter. The wife is not religiously obligated to go out to receive her husband's mother, but she must return the greeting. It is commendable to receive her and welcome her, for among the virtues of a wife's character is to treat her husband's family well and overlook their missteps.