Where is your granddaughter's father? Is he in the picture at all? If he is, do you have a good relationship with him?
Absent any proof that this man (or your daughter) is a danger to your granddaughter, I doubt there is much you can do.
I suggest you have a consultation with an experienced Family Law attorney to go over your concerns, as well as to find out your legal rights and responsibilities. If you don't know an attorney, contact your state's Bar Association and ask for a referral to someone in your area.
Also, be sure to keep the lines of communication open with your daughter. You don't want to end up out of the loop, wondering what's happening to your granddaughter and desperately trying to find out from a third party.
Can you make arrangements to regularly see the child? Perhaps a regular weekend visit, or an overnight one night a week (at your house)? If you keep in contact with them, you'll be more likely to know when (if) something happens.
In the meantime, there's always a chance that perhaps this man will turn out to be just what your daughter needs!
Best of luck to all of you.
