MIT and Harvard both have housing websites where open rooms are posted by roommates. Other than that, Craigslist is her best bet.

Maybe find a bar you can sidle up to at, like, 2pm? My last semester of college my buddy and I were done with class at 1pm three days a week. We found out (trial and error) that a pub in the early afternoon on a Wednesday was the perfect time to find a bored bartender looking for something to kill the time til happy hour.