Danite: If the goal is biggest bang for buck in that hour and she has space could do oil and a fan heater. Fan would get the room warmed up in that hour and oil heater then back the heat for the longer term.
instead of the fan heater, just buy a normal fan (that might be in handy for summer). both heaters produce the same amount of heat. a big fan going slow is great for moving the warm air around quietly.