When Illiryia says Fred's sold was destroyed in the apoy s ogres erection, does that mean Fred went to Hell? Or did that mean she just couldnt be brought back to life?

It doesn't mean she went to hell. The "fires of resurrection" are most likely a modernization of the ancient Greek idea of the "Logos" or "fire of creation." This far pre-dates the idea of an eternal punishment in the form of a fiery hell. It is likely just a way to say that Fred's soul has been destroyed forever, putting her in neither heaven nor hell.

I interpreted the phrase to mean that in order to resurrect Illyria, Fred's soul had to be destroyed. She's no where, because her soul no longer exists.