Heartsteel
Heartsteel is great against squishies (and in general), and gives you some tongue range (and speed) to catch her easier.
Swiftness Boots
I default swifties, but I think it's very good here. Tabis sounds nice on paper but it's way more expensive and way less movespeed, so the idea with swifties is, yeah, you're blocking less damage per hit, but you're catching her faster and therefore not giving her as many free hits anyways. Plus, the passive doesn't mitigate her E bonus magic damage, and I don't think it mitigates her passive either.
Riftmaker
Riftmaker is really good when ahead, which will usually be the case when you're used to this matchup! Really though you have a lot of options, and I would take into account the game wholistically!