ooh, I missed that requirement.

However it's not a problem since she already has a dumbphone; Of course it depends on the phone but I used to do wlan sharing with my phones in the days of Symbian so I suppose she can use the phone to tether the tablet..?

Another option would be to connect a usb-stick cellular modem to the tablet; not an optimal solution since it most probably would require usb-a/microusb adapter and the stick would dangle out from the side unattractively.