Do you think my girlfriend should have done this?

My girlfriend is 6 months pregnant and last month she went with my mother to register for the babyshower which my mom is throwing for her. My girlfriend picked out the stuff she wanted for the baby but last week my mom switched all the stuff my girlfriend picked out with stuff that my mom liked better.the crib, the stroller, the blankets I mean almost everything. when my girlfriend found out it was already too late because the stuff was already bought. My girlfriend called me saying that she is finished with my mom because she is too controlling and thinks that just because she is throwing her the babyshower that she gets to control everything about it. My girlfriend was extremely angry and now says that she will not even come to the babyshower. My mom says she is bring spoiled , prissy, and ungrateful. Who do you think Is wrong? I need advice in this situation.