The idea of a curtained bed reminds us of the narrator's current cell. Which is stronger, flames or bars? Could you do a symbolic reading of this moment?
It was with great difficulty that my wife, a servant, and myself, made our escape from the conflagration. (10)
The word "escape" would seem to speak to the "freedom" part of this theme. It seems, though, that there can be no escape for this tragic couple. When we move, we take most of our problems with us. If we move because our house is burned down and we've lost all our money, we move with even more problems than we had before.
For months I could not rid myself of the phantasm of the cat (13).
The "phantasm" or "ghostly figure" in question is the image of the hanged cat the man found on his bedroom wall after the fire. This image traps him.
I had walled the monster up within the tomb! (32)
Now that's an ultimate moment of confinement. It doesn't get much more confining that being shut up a wall with a dead person.