(((((((((( Maven & Mom ))))))))))))
I'm so sorry to hear of your mom's illnesses and all. I will keep you both in my prayers.
Maybe you could ask at the rehab if your mom seems to be having hearing issues or if their phone system is not working properly.
I remember when my mom was ill with cancer, many of her friends didn't come around or call during that time. It made me angry because I knew it hurt my mom's feelings. I came to realize later on that those things happen mainly because those friends don't know what to say or do and sometimes they are just scared.
Maybe you can get your mom some notes and envelopes and stamps and she can write to her friends. That may help her not to feel forgotten and that there is still connection. They may even send a card or note back to her and that would be something she could hold onto and look at and read when she's feeling lonely.
Take good care of yourself and know that I hope the best for you and your mom.