A point to be made here—clearly, said mother hasn’t been calling them very often either, so…it goes both ways, at the very least.
When my mom was alive, I would call her fairly frequently….or I would hear about it.
Now I wish I could call her.
my mother died when I was still in high school so I was never away enough to call her, and my father died a couple years later when I was in university. I called and talked with him about 2 hours before he unexpectedly died of a heart attack. I’m almost as old now as they were when they died and have always wished I could have talked with them again.