Is it permissible for a needy person to take charity money that he was asked to deliver to another poor person, especially if he himself does not possess his daily sustenance?

If a donor gives you money to deliver to a specific person, it is not permissible for you to take it for yourself, even if you are poor, because you are an agent on their behalf and are obliged to deliver it to the designated recipient. If you violate this and take the money for yourself or your family, it becomes a debt upon you that must be returned to the recipient whenever you are able, unless the donor forgives it.