What if your dad just passed away with lots of debt but all the money in his estate is from Social Security Disability is this money exempt from creditor garnishment?

Your father's assets became a part of his estate. His debts must be paid from his estate. You need to file a probate so his creditors have notice of his death. They can then file claims against his estate. His Social Security stipends should have been used to pay his debts.

If the claims become too complicated you should seek legal advice on how to pay them. There is a statutory scheme as to who gets paid first. If the debts aren't paid according to the provisions of the law the people in charge of his assets can be held personally liable.