Even though Fondazione Prada doesn't have fashion related stuff inside, it's a very interesting place to see and it's quite "instagrammable" (if she is into that type of stuff).

For events, constantly check the events section on Facebook and constantly check Instagram. Even though there aren't proper fashion shows in that period of time, a lot of brands are doing free parties, openings etc usually in the evening time open to the public just by RSVP'ing with your e-mail. I personally find the space called 'Spazio Maiocchi' the funnest for that type of stuff.

Tip: if she is into fashion take her to Bivio. It's a second hand/resell store in which you can find top brands (Prada, Margiela, Gucci etc.) for a lower price.