Grandparents regaining custody of grandchild

When my grandsoon was born, he was positive for meth. Child protection stepped in and he temporarily went to foster care. Because my daughter had warrants for her arrest, she turned herself in and actually went to prison. We (Grandparents) were given custody.. daughter granted custody to us rather than risk loosing her son. In prison, she was given an opportunity for early release if she completed a touch love boot camp. After nearly 2 years she was released. Found a wonderful job.. eventually regaining custody. That was nearly 3 yrs ago. Since she has purchased a home and was doing extremely well, with the exception of allowing a lazy, drinking boyfriend to move in. During the last several months she has had several crisis with this boyfriend. Missing alot of work etc. Distancing herself from us with one excuse after another. Now she is obviously neglecting our grandson. He's only 6 and many days getting up by himself, dressing himself and going to summer program. He's not being fed properly and more times than not is clothes are dirty and unkept. She has admitted using since her release, however, insists not currently. I know she's building a smoke screen and when she uses the norm is lying. Is there any chance of regaining custody since this is the only other home he's had, or would his father be able to get custody? Thanks for anyones help