It’s so hard at this age to understand what’s going on in their mind. Does she spend much time with your mum? Alone and with you? What’s the dynamics normally?
What about if you go out somewhere with your mum or go to your mums? Does she spend time alone with your mum or is it always at your house? It's a difficult question but could there be any chance of a sinister reason you need to explore? I'm wondering whether it's jealousy that she doesn't know how to express? If your mum is one of your favourite people and she's needing to act out to gain your attention? I remember once, my nephew told me to go home because he didn't want me to be there anymore (he was about 3 or 4) and I was so upset but in hindsight me and my sister hadn't seen each other for ages and had spent the morning shopping.
Before I read the part where she said she doesn't like your mum, I was going to ask what their relationship is like. I would be asking why she doesn't like grandma or what grandma has done to make her feel like that. And maybe also tell fun loving stories from your childhood with your mum. Is she the same if it's just her and grandma?
If she is saying she doesn't like your mother, although it might be upsetting to you, it is vital you try to understand why your daughter feels this way about your mother without judgement. So try to talk to your baby nicely and understand why she feels that way. If you get mad at her, it would discourage your child to speak her mind and express emotions freely x sm