Should the deceased worker's entitlements be handed over to his family or to his colleagues who claim he is indebted to them?

You are not obligated to pay money to those who claim a debt from the deceased rightful owner. Instead, they should take the matter to court to prove their rights and claim them from the deceased's estate. If they refuse to do so, then you must send the money to the heirs. This is because a mere claim of debt is not sufficient, especially concerning the deceased, where some scholars deem a judicial oath necessary. Furthermore, there is the issue of creditors: perhaps the debts are numerous, and the estate is insufficient to cover all of them, in which case the creditors would share proportionally what is available.