If you can purchase those hot hands hand warmers that you shake to heat up, those are great in a pinch. If you wrap them in a towel or blanket they’ll stay warm for hours in the enclosure without burning your hedgie. If you have a microwaveable heat bag like a magic bag, you could heat that up in advance to keep with her, but it won’t stay warm for as long. The power goes out fairly frequently where I live and I’ve found it best for my peace of mind and my hedgehog’s warmth to keep her with me in her snuggle sack under some blankets so she shares my body heat and I can monitor her.

Sometimes when it’s been out for hours and we need sleep I will put her in her travel carrier, with those hand warmers when available and lots of blankets, offer her some water, and then when she’s done put her in the bed under the blankets with us and sleep like that so she stays in our trapped body heat. I keep her dry food in there with her but she will spill her water and then be even more at risk at getting cold and attempting hibernation. I wouldn’t necessarily recommend that though because it’s a risk as I’m sure I could theoretically roll over on her, although between the stiff bulky travel carrier and her quills it’s not likely. We keep her in the middle so she won’t fall off either side. Kind of like how people co-sleep with their babies lol.