@awesome777yay As a mother, I feel horrible for these children and I'm disgusted at the lack of care this girl takes for her babies.
First off - yeah, call CPS. Get those children into a home (whether it be with other family members or a foster) that will love them and give them a clean, comfortable environment to live in. No child should ever be ignored like that. My soon to be ex-sister in law does this with her children - lets the youngest walk around in the same diaper for up to 10 hours while my brother is working, leaves the house in such horrible shape that family won't visit, and so many other things. So yes, get those children help. You obviously care about them, and if no one else is going to do it then I think you have a humanitarian obligation to do what you can.
As far as finding her parents or other family - CPS and the courts can do that. I wouldn't worry so much about that aspect.
Finally, your friend also needs to get some help - therapy, medication, whatever it takes. She sounds like she is in a deep depression or serious denial, and she is trying to fill that void with a man - ANY man will do. Getting CPS involved will either wake her up... or she will continue this way and show that her children do not take priority in her life. Its a sad situation all around, and I hope you can get something done for all three of them.