Grandmother being petty

So my grandmother is very rude sometimes...most of the time. She loses her patience when she's around my kids as well as my brothers. She snaps at them and calls them names. She once snapped at my brother's 1 year old son because he was babbling. I don't like this. My mother doesn't like it and my kids don't like it. It's not even them misbehaving they literally do the smallest thing and she'll snap. My son is 6 and he doesn't like being called a baby. It really bothers him and she continues to call him a baby. My mother confronted her the other day because it was bothering her. She told her that she doesn't like that my grandmother keeps calling them names like "baby" or "drama queen" and snapping at them for every little reason. I used to ask my grandma to babysit when I had appointments I couldn't take them to but I stopped awhile ago and now just figure it out with them. One main reason was because they misbehaved once and I didn't like it so I stopped taking them because I don't think anyone should tolerate my kids bad behavior and that was the first time they behaved that way. Another reason was the name calling and it hurting my son's feelings. My son is on the spectrum, he has meltdowns sometimes and when he's having one of these meltdowns we all try to keep calm and let his meltdown pass. Well my grandmother starts screeching and telling him to stop being a baby and that makes the meltdown worse. So when my mom was talking to her about this she instead got mad instead of trying to understand and saying she'll try to be more patient. She said "if he doesn't want to be called a baby then don't act like a baby". My mom told her her generation is all about yelling at kids and calling them names and they think that's how it is handled. So this Thursday I'm giving birth. My grandmother was set to watch my kids but now she's saying she has a dental checkup and can't do it. That's fine. My mother is going to watch them. My mom is mad because she wanted to be there for when my baby is born but she'll visit later. I'm also going to tell my mom I don't need my grandmother to come over to my house to help me because I know it's not going to be helpful. She'll spend the day yelling at my kids for the smallest things and I'll be trying to recover with a new baby and I don't need that. I don't need stupid pettiness especially with grown ass adults and if you can't watch my kids when I'm in the hospital giving birth, I don't need your help when I'm home.