You assume they were fully aware of the effects such actions would have on her, and fully aware of her condition. Kids and teenagers can be evil, but they often don't know what they are doing. Unless it can be proven that they did, they shouldn't be charged with something so severe - if charged with anything at all. The parent involved, however, I could see getting charged with severer penalties, but again only if it can be proven that she was fully aware of the consequences her actions would have.
This is the parents looking for someone to blame because they wish they could have done something different in hindsight and don't want to blame themselves. Should the kids get into trouble? Sure, but don't go overboard with the felony murder charges (the adult withstanding)... Karma will come around eventually. It always does.
She obviously has some major problems that need to be addressed.
I'd say at least manslaughter or something.