How do you expose a narcissist mother-in-law?

As a mother of a son, I can tell you that you kill her with kindness and set limits. Smile when you see her and ask her opinion ( you don't have to follow it, but ask). Be her friend. She is narcissistic our of loneliness. Fill that lonliness and the negative behaviors go away. For example go shopping for an hour and have lunch with MIL then you get the evening alone with your husband. She might have some good features if you look. Pushing her away will cause her to pull harder. In the end you loose your sanity and peace. So make a little room for her and she will stay in the little room. good luck joymaker.