Is it permissible to give the mother a portion of the the charity money designated for distribution to the needy if she is in need of money to meet her basic needs and medical treatment?

If someone appoints you to distribute alms (sadaqah) to the needy, and your mother is needy, there is no harm in giving her from it. As stated by Ahmad in "Al-Mughni" and by the Hanafis in "Al-Bahr Al-Raiq," an agent (wakil) may give charity to his father, son, or wife if they are in need. However, if the owner of the wealth tells the agent, "Place it wherever you wish," then the agent is permitted to take from it for himself.