Who would get custody?

This all started last year and is a very long complex story, last year a teen girl came from Wisconsin to Tennessee to live with her boyfriend's mom because her boyfriend was in jail and they had a 10 month old baby. Well in May? she went back up there because she was homesick and didn't take her daughter back with her. The boyfriend's mom let my mother keep the baby a lot and she would take her places and my mom just fell in love with this baby. So in November Lilly's mother came back down here and took her daughter back. She would call my mother weekly asking for money for diapers and food and just things like that. We tried to call child services but because we are not related to the child there is pretty much no hope for my mother and father getting custody. So now the little girls mom and dad are both in jail for the next 3-5 years and she is staying with her psycho grandma (she cussed my mother out on the phone when she was trying to get an address to send diapers) and from what we've been told she is a heavy drinker.. So basically who actually has custody of the child? I know my parents probably have a better chance of winning the lottery than getting that baby but can her other grandma try and get her? How would she go about doing that? Is it easier for grandparents to take custody of a child from each other than a grandparent taking it from the child's parents? And since we live in different states, does that make it harder to get her? We just want what's best for the baby, and we all know she isn't safe up there.