(1) By security money, if you mean the pagdi and advanced amount of the house. It is not right to increase it and decrease the house rent; it falls under riba (interest): كل قرض جر نفعاً فهو ربو
(2) You can give your house to others for the sake of safety whether without any charge or on rent. However, it is not lawful to have interest based dealing.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband