Agreed with Grace. Get a CHE set up as soon as you can. If you can, keep your room or house temperature to at least 70 until then. Talk to your mom and stress how important it is for the health of your hedgehogs. Mention that if they do get cold & attempt hibernation, they could easily get a URI. That requires a vet visit and medication. It'd be cheaper to keep the house/room heated to 70-73* for a night or two than to pay for the vet visit.
If your mom refuses to let you get a CHE set up or space heater for your hedgehogs, then for their safety, you need to find them a home that is able to keep them warm enough.
~*~*~ Kelsey ~*~*~
RIP my sweet Lily ~ 6/12/08 - 1/20/12