Mum doesn’t like coming home now

Ever since my grandad passed away last Saturday 13th Feb, my mum has only been home one night. She says she feels comforted in my Nan and Grandads home.
She was staying there for a week before the passing also.

She says she feels worse at our home.
How can we help with the transition? So that she feels better at home also?

Myself and my sister have been staying at my Nan and grandads home on a night on/night off basis with my mum and Nan.

Also, how do you get over the images in your head of the last few minutes. We were all holding his hand and it was quite hard to watch, that’s all that keeps replaying.

Is there a time frame for when shock passes? I still do not really believe this has happened?