Tolarian Wind is right, get your passport ASAP (fortunately you don't need to specify country or date of travel when applying!) You may already be too late to get the passports back by September 1, although I suspect late spring is their busiest season.

Is this trip a surprise? Telling her to apply for a passport may give her a clue that something's up

Changing subjects, when I went to Belgium last year with a friend who had never travelled, her biggest concern was "Do I bring travellers checks or cash?" I told her to do as she does here: find an ATM, insert card, punch in PIN, withdraw cash in local currency. You'll get the best rate, and it's convenient. Plus, if you have an account that doesn't charge for using ATM's outside the USA, you can even withdraw smaller amounts at a time; if they charge (typically $3/withdrawal) you'll want to withdraw the maximum (to minimize fees), but personally I get uncomfortable carrying that much cash with me.

Oh - and make sure your PIN is exactly 4 digits, many foreign systems require that.