By Castleknock Hotel, I take it you mean the relatively new Castleknock Hotel & Country Club. It is on the Porterstown Road, between Castleknock and Porterstown. Any B & B in Castleknock Village is too far to walk, particularly at night, although it would only take 5 minutes in taxi. I can't think of any B & B within walking distance of the Hotel - I don't think there is one.
Past30