I'm not sure I understand the question. Do you mean there is an unsatisfied mortgage against the property and the mortgagee - the lien holder - has died?
The fiduciary for the estate or the heirs of the deceased can sign a satisfaction document. Have an attorney review the matter and prepare the document. If you can't locate the parties, have your attorney start an action to quiet title. Don't dilly dally because it may take time.
Depending on the circumstances and the age of the mortgage, the title insurer may consider an escrow pending resolution so you can proceed with your closing.