Probably not. As a rule of thumb, take whatever "speed" a wireless gizmo advertises, and divide it by two to get a real-life baseline for any use that doesn't happen within the same room. In your case, this (26mbits/sec) is still faster than your Cable modem, so no loss here. This gives 15mbits/sec over the first wireless link.

Then divide by perhaps two again, to account for the (half-duplex) relay.

So in her setup, I'd expect to be able to stream at a steady 7-8mbits/sec in real-life. Maybe better, if the sun, moon, and planets are in The Correct Alignment.

Cheers