I believe the buckle is a sash buckle. I had found a silver one much like it and found it was an accessory to a late 19c. nurse's dress. It had the same type hook. I think yours is from around 1880s to 1890s I also think the door latch mechanism is from around the same period. The door latch has value and can be restored. I've been in an antique store that actually does restore and resell old hardware like that and the prices when finished are up there.
Coming back to the buckle it looks as if it has pierced symbols of some kind. I checked out the masonic eastern star, but not seeing much. Could be for a fraternity of some kind?