I have had two ablations, the first one in Jan '08 the second one in March '08. After the one in Jan I was VERY VERY tired. For about the first two days I didn't care about doing anything except sleeping. I would wake up, go out in the livingroom for a bit, and then turn right around and go back to bed for a nice long nap. My husband was getting pretty worried that I was abnormally tired, but by the third day I was feeling much better, not at all as tired. I don't know for sure what it was that made me so tired, but it didn't happen after the second one.. If you're really concerned you could give her doc a call, but from my experience it sounds like how I felt. Her body may just need time to rest and heal. BTW, I'm a 28 y/o female.
Medication may responsible for the symptoms. Does your mother take a beta blocker?