I'd go back.
But I'd tell her straight up that you're her mother and if she pulls anything lime that again it'll be the last time she's around your child because you won't trust her.
I'd also bring something for your daughter to sleep in in the room you're staying in.
When your mom brings it up, tell her it's your choice and that's the end of it.
It's not your dad's fault so by staying away you're hurting him.
Be prepared to follow through with staying away though if she over steps her bounds again.
I had to cut my mother off for several years for ignoring my choices and putting my kids in danger. She didn't believe I'd follow through. She believed wrong.