I am worried about my Great Nephew. His mom is a phsyco what do I do?

First of all he is only 3 weeks old. His mother almost drowned him (on accident) cause she didn't know how to bath him. She laid him down in the bathtub on his back and ran water up past his ears almost covering him. His Gma ran in and saved him. Then come to find out she is brushing his mouth with toothpaste cause she says his mouth stinks. He is only 3 weeks old and has no teeth. His other Gparents are feeding him icing off of a cake and she is giving him pedialite. She has no clue what she is doing and won't listen to any of us. The daddy who is my nephew can't even get her to listen to him. She ignores all of us. We are so afraid that she is going to seriously hurt the baby and we don't know what to do. Please can someone help us?