Take a look at Power Line Networking. Plug one unit into ac near your router and connect Ethernet cable then plug other unit in Daughters room and connect Ethernet cable. Can also be encrypted if desired.
Newegg.com - Powerline, Powerline Adapter, Ethernet Bridge, USB Powerline Adapter, Powerline Networking Kit, Powerline Ethernet Adapter
I gave up on WiFi for my wife's laptop and the Power Line works great.