Is it permissible for a sister whose brother has passed away, leaving money in her care, to spend from this money on his washing and burial, and to prepare food from it for the mourners, or is this money rightfully for the orphans?

What remains of the deceased's money after his illness and preparation for burial is considered a trust in his sister's keeping. Whatever she consumed improperly is a debt upon her, which she must return to the heirs. Preparing food for mourners is an innovated Bid'ah, as the Prophet, peace and blessings be upon him, said: "Whoever innovates into this matter of ours something that does not belong to it, then it is rejected." The matter becomes even more severe if it is from the money of orphans or heirs who do not consent to it.