The bedroom is at the rear side of this house.

Answer: Option B

Front : the side or part of an object that presents itself to view or that is normally seen or used first; the most forward part of something.
Back : the rear surface of the human body from the shoulders to the hips.
Upper : situated above another part.
Different : not the same as another or each other; unlike in nature, form, or quality.
Rear : the back part of something, especially a building or vehicle.

Synonym of Rear is Back