I thought she might be a student when you mentioned spring break. Does she teach at the large American school in Maadi by any chance? I was at a 4th of July party in 1999 there. When I and other American students entered the compound a band was loudly playing "Achey-Breaky Heart". One person said "This is the reason Americans are killed in this country". Heh, gallows humor in hindsight.
99.9% chance your sister was nowhere near the blast. So many resorts on the Red Sea and just thirty people from one.
Yes her school is in Maadi. It is Misr American College
She emailed me that they were going to the Sinai for snorkeling, and I remember her telling me that some of the best snorkeling is at the tip. Then later she mentioned the delta, so I'm really not sure...