What should I do to absolve myself and the deceased treasurer, knowing that I am the only one who knows the details of the "unofficial" amounts that were disbursed, while the deceased's heirs deny the existence of any association funds in their father's possession and insist on an undetailed disbursement slip that contradicts what is recorded in the deceased's ledger?

The questioner is only required to inform the association's administration and the deceased's family of the truth of what he knows regarding debts, and advise them to fulfill the rights of the association that are incumbent upon the deceased. For the deceased is not absolved of responsibility except by the settlement of his debts, and the settlement of his debts must take precedence over the distribution of the inheritance.