@Giacomo415 That's really rough... can you afford a crap review at this point? I know I was so stressed out last summer when one review brought down the whole rating since I had a new listing.
I'm not super-experienced so feel free to ignore my advice... maybe meet them halfway and give them one night off? You've already offered to help them find somewhere else so honestly I think it's up to you. The only thing I can think of for above-and-beyond is offering to drive them to their new listing if that's still a possibility.
I'm finding even with information in the listing some newer travelers don't read or just can't find the information they need right away. Maybe in future when the booking gets made just send them a message saying there's noise, are you okay with that? (This is something I read someone does for older homes that have normal wear-and-tear, they made a point of texting out potential problems in advance).
I did have someone ask me how quiet our neighbourhood was as they were a light sleeper. We're on a main road that's fairly quiet in the evening but has some noise bleed, plus some kind of e-bike organization that tends to scream down the road after dark. I let her know and she found somewhere else.
They definitely sound like they're nickle-and-diming it at thing point so it's definitely a balancing act. Keep us posted and let us know how it turns out, I'd love to hear any solutions for these kinds of problems that worked.