Aunt B. Needs Some Router Help...

[shilala]

Well, not router help, internet access help.
Here's the thing...
Aunt B can get wi-fi out at the back house where she lives. My FIL and MIL broadcast wireless from the front house.
She just got a new ipad, and it won't pick up the wi-fi back there, although her iPhone and her desktop do.
My thought is that we need an extender or booster or something.
It'd be very easy to mount something outside under the eve of the roof at the front house.

My problem is that I've never done this and I'm unfamiliar with the hardware. What do we need here? What can I install to boost the signal a bit so she can get her internet on?

This may be simple operator error, I haven't been over to check things out yet. I'd like to get learned up before I go.

Here's a wonderful diagram of said situation...