Shalom in Yeshua simik, I am saddened to here that your daughter is so upset by the passing of your mum, but at the same time I am not surprised. Children can go through the same emotional feelings as adults.
It is very important to ensure that it is her death which is causing her to cry. Are you sure that it not something else, or a combination your mums death and something else. If it is just your mums death, then she needs to be comforted, cuddled and re-assured. Ths may take some time but children are very resilient and things should settle down after a while.
Moving to your mums sounds like a good option, and may comfort your daughter to be in her nans but it depends on your abilty to afford to live there. You must also ask your little one how she feels about it.
I will keep you both in my prayers this weekend.
May God bless you