Need suggestions for Moms lonilness

I am a 25Y old working professional. My mother suddenly became lonely as we (her children left the house). Before that she had a routine life along with us. Now she cannot even leave home on a regular basis because she has to take care of my grandparents (one having dementia and the other one is paralyzed). She really doesnt have any one to talk to, we cannot talk to her in office hours and this is the time she is mostly lonely. She does not have friends with whom she can share her feelings. I feel very helpless in this situation. Can someone suggest some ways by which I can keep her busy?