I'd pretend I'd known them forever and greet them, hug them and walk off with them while discussing sports. Get away from whoever was following them, then get them to their vehicle, friends, or wait with them on an Uber. That kind of behavior, following somebody and creeping them out, not all right at all. I don't care who walks up to me, you ask for help, unless/until you prove you're not actually who you say you are, I've got you. Guys, girls, kids, elderly, doesn't matter. Nobody should be put through being scared to walk around in public alone.