Vanessa,
I am so sorry to hear this. I lost my prescious grandmother several years ago and I still miss her very much. She had dementia and did not know who I was or who any of us were when she passed away. The important thing is that your mother and everyone else is there with her now. I'm sure she is comforted by your mother's presence. I pray that if it is her time to go and be with the Lord, that she passes peacefully.