My mother-in-law didn't send condolences when close relative died and mum sick and then stopped communication?

You cannot make someone care, it has to come from within them. From the sound of it she does not seem interested in your lives at all, not even from the time you were married. Focus on your own family and your side of the family. My in laws have never once asked me anything about myself or my family in 34 years, not once. Some people are just very self centered.