Every time my in-laws quarrel, my mother-in-law keeps complaining. How to solve it?

I think that every time my parents-in-law have quarreled, my mother-in-law has been complaining to herself. The most effective way is to tell her that she is so old and the couple have been here for so many years. If there's anything you can't stand, you have to quarrel every time. At the same time, I also take my own example and tell her the reasons for my happy life with my husband. Tell my mother-in-law that the way to live happily with her husband is to be tolerant and understanding, and I hope her mother-in-law can understand her father-in-law, so that the contradiction between her mother-in-law and her father-in-law can be solved and the problem of complaining to herself all the time can be solved.