1) Did she want to steal the car or maybe she just wanted to punish the owner for having parked on her spot?
2) For sure her housekeeper (or her husband) had thrown away something very important or valuable for her.
3) Maybe that man had delivered something to your neighbour and was waiting to be paid.
4) It might be possible they were coming from a party and they couldn't drive because they had drunk too much.
5) Maybe he had heard some suspicious noise, put on his rubber boots, and when he got out he forgot to take his keys....
6) It might be possible the young man had lost his eye glasses, or a contact lens and he was searching it