Where do i turn to about a family that is always on drugs and have to be monitored?

My daughter's boyfriend was incarcerated in Livingston county Michigan 2 weeks after my granddaughter was born for being under the influence of drugs and beating me up (my daughter's mother). I had put him in jail and he violated his felony probation. He has been released and is threatening us. My daughter went to his mother's where he is staying since he is the father of her child to have a family visit because he hasn't seen his daughter for 8 months. But they are violent drug users and have gave my daughter drugs today I seen her and they are putting her in danger. Who do I contact for someone to monitor this sick family.