Should i call child protective services

So I have a niece I believe she's 18 , she does drugs in front of her 1year daughter and nobody seems to be bothered by it. My sister in law is aware of this but has never done anything to help her daughter or granddaughter, she's become really agressive, not that long ago they got in a really nasty fight and left scratches and bruises all over my sister in laws face and arms. She didn't do anything about it. Oh wait ...she did ...she avoided the problem and left to mexico 😒and is still over there, she's never been a responsible mom she tries to ignore all her daughters' problems. My question is, if I call cps can I do it anonymously ? Will my sister in law also be in trouble because of her I don't care about my daughter attitude? I don't want to get too involved but someone has to do something for this innocent child. I need some advice please.