As long as your office does not have 18" concrete between the upstairs and downstairs, and the router is placed as high as possible and unobstructed, it should work.
If signal is too weak, the Netgear Powerline adapters or Zyxel work through brick walls through the power outlet lines. But I think it should not be needed if your computer downstairs can connect to the WiFi with a good signal.
If your computer downstairs in the office is hard wired to the network, I suggest hooking up the printer to the hard wire connection as well, if at all possible. Scanning works best when you have a good connection, and scanning over weak WiFi might be a problem...