Thank you for your response.
Our only wired PC is connected to the router, which - in turn - is connected (through a short coax cable) to the outlet. This is, basically, the outlet I described in (B). If we went with (B) we'd put an additional splitter at the end of the cable that currently goes to this outlet. The rest of our devices (laptops / smartphones / tablets) use wi-fi.
Thanks again.