I recently finished a spare room to move my mother into. I added 2 vents from our forced air furnace but the room is much colder that the rest of the house. It is very close to the furnace so I think this room should be really warm. The furnace is located in the basement.

Did you calculate the size of the vents to the size of the room? If not now is the time for you to do that since the duct serving those vents might be to small.

Is a return air needed? You can blow heat into a room but unless it has some way of returning the cold air back to the furnace it will probably not work.