How do we communicate w/Mom who has just lost all of her hearing in both ears

Six weeks ago, or so, my Mom with dementia seemed to be holding her own in the ALF she's in now. She was the life of the party. Even though her hearing was limited to one ear, she would communicate w/the other hearing aid in her "good" ear or lip read. On a visit day w/my sister, she couldn't believe what she saw. Mom was in wrinkled clothes, hair a mess and just sat in her chair by the window not looking at much. We took her to the doc to get a new hearing aid, figuring that was part of the problem. That wasn't the problem. Took her back to doc, he performed some tests and declared that Mom could not hear - at all anymore! She slipping downhill very fast now. Total incontinence, comfined to a wheelchair as she doesn't have the stability or strength to walk, the visits are devastating for us as she does not talk much anymore and she does not recognize either my sister nor me. She does have a great appetite however, just like all her life. Our question is there something we can do to communicate w/her. We feel so helpless and cry all the way home because she's not Mom any more. Can you help...even just a little bit? Thank you, Teri PS: She's 91