Sharing Internet via Network Cable

My husband’s niece has transferred to their newly remodeled house. She used to stay in a room just adjacent to our house. Internet connection was not a problem then. But now, since her new room is quite far from where the router is located, my husband has no option but to relocate the router so that she can connect to the internet via wifi as she used to. Hubby has to install a new network cable wiring using cat-5 twisted pair cable.