Is there a legitimate legal way to pay off the debt of a deceased person who had taken work equipment from a foreign company that no longer exists?

If you are certain that your father took company equipment as an act of usurpation, then it must be returned to the company or its owners. If you despair of finding them, then donate it as charity on behalf of the company owner. This applies to all usurped funds, deposits, and borrowed items whose owners are unknown; in such cases, they should be given as charity on their behalf. Hasten to do this and seek forgiveness for your father, for breaching trust is a grave sin, and some jurists have counted it among the major sins.