A ceramic bulb might be a good choice. They do get quite hot so a guard on the lamp is a must. As a former reptile house zookeeper I can tell you that these work great. Especially in a small, enclosed area, they'll heat things up quickly.
So sorry for your loss, and I hope your others pull through.
It's very cold here too, and will get colder, down to 11 at night by Saturday. Our big roos were raring to go this morning & don't seem to mind being outside but our silkies and Polish have been brought indoors.