Is the wife wrong for defending her husband and for avoiding going along with her mother's bad opinion of him, and what should she do when she appeases her and ignores her?

Do not exaggerate in praising your husband in front of your mother, lest you ignite her jealousy. Avoid imposing your way of thinking on her or making her feel that you understand better than her. Absorb her anger towards your husband by clarifying that he is a human being, not infallible, and never publicize her mistakes. Try to improve your mother's relationship with your husband by encouraging him to be kind to her with good words and gifts. Finally, if you are forced to choose, prioritize your husband's satisfaction over your mother's to preserve your home.