I suggest that the best way to help your mother would be for you and her to consult with a Wills and trust attorney with a background in tax law.From what you have written, your father's estate where there is no Will and presumably no trust would be subject to a petition to administer the estate where the court will decide who receives what assets out of it. My experience is that your mother as the widow will receive the lion's share.If there are enough assets of the estate, by all means your mother should continue making the mortgage payments on the home pending advice from legal counsel suggested that she see.Your father's estate would be subject to creditor's claims including the 401 k.