I don't like to scare you,
get her to change her routine, is she walking the same route, same time, same routine on a weekly basis,
some of these men, start to stalk, having spotted a girl that interests them, ask her to think if she has seen the van before,
it just we have had more than a few of these incidences over the last few years, one of our village (15) girls, was nearly snatched after leaving an after school activity, she really did fight back, and luckily a father of another girl drove past, and saw the man trying to drag her into the van, guy drove off as he intervened, on quite a few of these the man had been watching for a while,
she must stick to inside of the pavement, if she feels any unwanted attention, go into the nearest shop, or business, explain the problem, wait in the business, until parent or police arrive, also go up to the front door of a house ring bell, ask home owner to phone police
carry taxi money,if you get a cab, let someone know the cab number, keep phone charged, take photos of suspicious vehicles,
choose safe routes, tell someone where you are, tell someone where you will be, check in,
Walk with friends, no head phones.
be careful with her details on line,
Understand that being over cautious with her personal safety is not silly, it essential.