In law dynamics - what should I do

My parents and in laws used to get along great until we had a baby

Then there were a few instances where they felt the other person was upset etc then they didn’t contact each other- in an effort to keep the peace I had my mom call my mil and I thought everything was ok but my mil never calls her so now my mom is going to visit her sister in the same city where my mil lives and my husband asked if my mom told his parents she’s going —- but my mom isn’t going to call again when his mom never reaches out. How do I politely communicate this to my husband? I don’t want to make it sound like my mom cares for his mom to call bc she quite literally doesn’t care but at the same time it takes two to make this work