When my DH was first diagnosed he was on an antidepressant along with Aricept & Namenda and he still had periods of crying but they were brief. I really don't know if an antidepressant at this point would help but I would check with her doctor. My DH was pacing at the end with high anxiety and there were meds to help relax him so he could be calm and peaceful. This might be something to look into for your Grandmother.

Good luck,
Janie