Final answer:
Trevor knew Maylene as c) someone from across the street, as they were acquaintances in a small town who occasionally exchanged greetings.
Step-by-step explanation:
To answer the question of how Trevor knew Maylene, based on the provided reference, neither a), b), nor d) are correct. Given the details, "We weren't friends, really, but I knew her name and a little about her work and family. This is a small town, and if you live here long enough, you run into a lot of people.
She and I said hello occasionally at the grocery store or library," it can be inferred that Maylene was c) someone from across the street. They were acquaintances in a small town who would greet each other occasionally in passing.