If the house is in your name - and your daughter and son in law are not legal owners (not on Title), their debts cannot be attached to your property.
However, you may want to consult with an Attorney to discuss your arrangement with them as sometimes arrangements with family members can turn into nightmares.
We sometimes try to do too much for our children and it can come back to haunt us. Having second thoughts on an arrangement like this is very understandable.
However, if you are the buyer of records and the debt/lien is in your son-in-laws name only, it's unlikely that you would be held responsible because of buying and renting to them. This is only my personal opinion, not to be considered as legal advice. Always consider contacting an attorney for legal information.