Must a person return the financial aid received for treatment after his treatment costs have been reimbursed by the hospital? And is it permissible for him to dispose of the money from the municipality that arrived late and was designated for treatment, especially if he believes that it will not reach its treasury and will be used by officials?

It is obligatory to adhere to the condition set by the donor or the granting entity. If the money was given to the supplicant as charity, then he owns it, and he is not required to return what remains after treatment. However, if the intent of giving the money was solely for treatment, then the remainder must be returned. Scholars have mentioned similar cases, including what Khalil stated in his Mukhtasar regarding the mukātab (indentured slave), what 'Ulaysh said in Minah al-Jalīl, and what Al-Nawawi mentioned in the chapter on Zakat in Al-Majmu' concerning the ghazi (warrior) and the ibn al-sabīl (traveler).

Therefore, the consideration turns to the intention of the benefactors to determine the ruling on the remaining money. If the supplicant does not know their intention, he must explain the true situation to them, so they can decide whether they will reclaim the money or permit the supplicant to keep it.

As for the municipality, if returning the money to it would end up in the pockets of officials without entering the municipal treasury, then he should not return it to them. Accordingly, if what the supplicant says is true, he must spend this money on various types of charity and acts of righteousness, due to his inability to return it to its rightful place. This is because money whose owner is unknown or cannot be returned to its owner should be spent on the welfare of Muslims, as mentioned by Ibn Taymiyyah.