I am buying a house from my grandparents, the house in under *** family living trust, when we are filling out the grant deed do we write the family trust on it and their names or just their names?

If the trust is the owner of the house then the trust needs to be the seller.

I strongly recommend that you have this handled by an attorney or title company. It shouldn't be expensive and you'll know that it was done correctly. If you make a mistake it can be difficult to fix.

Ok if the trust is the seller do my grandparents just sign the grant deed?

Are they the trustees? Have you read the trust agreement? Do they have the authority to sign for transfers of property? Are any other signatures required?

Unless you are very familiar with what you're doing then you run the risk of really messing up the title to the property. Please have this done by a title company or attorney.