I know these things have been mentioned before, but:
1) Is she an experienced enough knife handler where you would trust her with a knife unsupervised, especially in a warm, wet, infection prone area with atrocious medical care?
2) Does she have the street smarts for places like this? I've known lots of very sweet and gentle "good kids" who are a ticking time bomb because they're TOO nice. I had more than my fair share of fist fights growing up, been picked on, had stuff stolen right out from under me, and I learned my lessons. I'm also a fairly well built male, and I still would be in pretty serious fear for my safety in those places. If she's anything like the kind of kids that I knew that went on missions, she's exactly the kind of person who would get taken advantage of.
I don't doubt for one second that she's good natured, well mannered, responsible, polite, and her cause is noble. I'm sure she gets good grades, helps old ladies cross the street and comes home at reasonable hours. She probably has pretty good self-discipline and I bet she handles herself very well with peer pressure and that kind of stuff.
But that's not what makes you a good knife handler, and not what makes you street smart. You have to get a few bad cuts before you truly understand the how's and why's of safe knife handling, and you need to get beat up and/or scammed a couple times before you really learn how to stay out of trouble.
That being said, nobody's last words were "I wish I did LESS cool stuff" and I think she has a lot to gain from a trip like this. I have a lot of respect for people who take all that risk, do all that work and travel all that way just to help out of the kindness of their hearts.
Back to the knives: I say a SAK or a Leatherman. Single blades are nice but nothing compares to a good multitool when you're out and about.
Also, some first aid training if she doesn't have it already. Remember that no matter how fast the police/fire/medic response, the victim is always the first one on the scene.
I know most of this is off topic, but this is a bit more important than our usual hobby chit-chat.