I had my problems with this quest too.
Normally I go into the house, in which the body of Benryn's wife can be found, and destroy the wall to the other house and safe Benryn.
This time it was very difficult and as I had rescued him, he falls down to the floor and I can't help him. In the questlog it is noticed that I saved him and he will not be harmed by the flames.
When I talk to him the regular animations about grieving his wife death and his aks to search for the hidden money like always.
