Dream of mother

My mother had M.S. for twenty five years and suffered greatly during that time. She passed away two years ago. I had a dream that my late mother was burried alive. We all thought she was dead but somehow they found out she was alive. The dream takes place in her room in the long term care facility she resided in. She was not well. I felt guilty that I did not know she was still alive and we burried her without checking. But I was really most upset and heartbroken that she has to go through more suffering just to die again. My mother was lying in bed. The room was dim. There was no interaction between anyone just my thoughts and feelings in the dream.