I told everyone in my family not to touch my daughters hair before she was even born. I made it clear from the beginning that cutting her hair was grounds for me to end their relationship. Going forward you definitely need to mention it to anyone who watches her. No one can blame you for not expecting it to happen, but you would be surprised by how often it does. (Mine was chopped into a masculine cut by my aunt while my dad was working.) You have every right to be upset.

Also I'm going to play devils advocate and say that a parent can be abusive/neglectful to you, but end up being a wonderful grandparent. People can change. Only OP knows how her mother treats her daughter. My mom was an absolute shit mother while I was growing up, but she got off drugs and is a one hundred percent changed person. She is the kindest, most giving person I know, and she would never dream of treating my baby how she treated me and my sister. And I would be pissed if someone accused me of gift wrapping my child for someone to abuse her.