Is it permissible to be compensated for the effort expended in finalizing the deceased's transactions and claiming his gratuity, without informing the heirs, and after deducting the expenses incurred?

It is permissible for the agent to deduct, from the agency funds, the equivalent of what he spent, in a reasonable manner, from his own money. However, taking payment for his effort is not permissible unless it is with the knowledge and consent of the principals, unless there was a prior stipulation or agreement on a fee. If custom dictates that such an agency comes with a fee, or if the agent is someone who customarily performs such work for a fee, then he is entitled to a customary fee (ujrat al-mithl). However, it is not permissible for the agent to take a fee without the knowledge and consent of the principals, as this would make him appear as a volunteer when he is not.