As long as she has a network card in her PC and you are connecting via ethernet yes it will be Linux compatible. In terms of BT compatabile AFAIK any router that has a built in modem will be compatible. I have used and set up a wide variety of routers, many of them on BT connections so you should be safe either way. I know for a fact that Addon, Netgear, and Belkin routers work fine with BT so if possible you could get one of these. The other option would be a modem that has an ethernet connection instead of a USB one, ut I don't know much about those so it may not help.
Hope this helped
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