Emperor's Fist and Skyhammer combintation
That gets my vote. My BA assault elements combined with my Guard tanks has always worked out great for me. Drop Pod/Deep Strike units are typically high priority enough that your opponent will have a hell of a time deciding which element of your army needs to be shot down first, and if you focus your efforts you may just kill enough to come out ahead before Tau do what Tau do and shoot the crap out of your army.
She might never want to play again if I bring two list or three different lists and put them out depending on what she brings.
Isn't that almost exactly what she does to you, waits to see what you have and then makes a list tailored specifically against it? Tau are a top-tier army from what I read about tournaments (which is basically nothing), if anything you
should be the one who gets to see her
list and then tailor to it.