Does the children's paying of the Zakat al-Mal on behalf of their deceased father—which was saved for buying a house and which he had not paid for two years—absolve his liability?

The heirs must pay the zakat for the past two years from the deceased father's wealth before distributing the inheritance, in order to absolve his responsibility, with the caveat that it is not permissible to delay zakat beyond its due time except for a valid excuse.