ASUS Wifi cards are pretty good, in general. Solid, multiple antennas etc.
I have a this USB 3.0 adapter: https://www.asus.com/us/Networking/USBAC55/overview/
And I can max out my 100MB/s download, although I have an AC capable router. I'm also in the same room, probably 10-15ft max from the router itself.
Since you only (appear) to have 802.11n (2.4 & 5GHZ bands), you're not likely to reach the 100MB/s, and the 5GHz band is more susceptible to physical interference (walls etc), which will limit it some.
All in all though, the ASUS adapter should be a pretty good option for your son if you're definitely going the wireless route. Obviously running ethernet, or even powerline would be preferred, but it's not a bad option if your connection is strong to begin with.
I'd mention though, install the Wireless Utility from ASUS's site - don't just install the driver & let Windows handle it. I had some stability issues when I first got it, but the Utility fixed it right up.