You know what ? I started to write trying to give advice but all I can remember is my first marriage, my mother in law was really a nasty woman. In fifteen years of marriage to her son I never once felt comfy enough to even make a cup of tea in her home.
I tried everything at first, I would take my sons to her house and my mums house alternate weekends so I was being fair even if my then hubby was working I would go on my own. Plus lots more but nothing was good enough.
In the end I just told ex hubby I was not going to phone her of visit her anymore I was also not going to 'remind' him to phone or visit with his mum.
And I stuck to my guns, it took three years before she broke and phoned me to ask what the matter was ! I told her and after that she made a bit of an effort (not much but some).
So I really should not be offering out advice to you

.
Hope you have better luck than me .....
PS just an after thought but I got on great with my second mother in law but my now hubby had a different relationship with his parents than my first did. My second would have a go at them if he thought he was in the right about something but the first one would just say 'oh let it go we don't live with her'.
Maybe there is a connection ?