I have to say I don't understand why the chickens weren't in a secure, safe coop in the first place.
Hi, Sugar. Maybe you can take a moment and think about it. The answer may come to you.
As I recall, the OP was assured that the dog would be taken care of "immediately," and they even trimmed the birds' wings just in case. I don't know about you, but I am unlikely to be able to plan, purchase materials for and build a new chicken run all in one evening. However, they did plan and trim wings, which is a job in itself--and deal with the neighbor--and doubtless bury the birds and comfort the poor little girl. Sounds like a full evening. I wonder if they had time for dinner? They may have been too sick at heart.
Simply because your responses to the situation would have been different does not mean the OP was unreasonable. My response would have been different, too... doubtless I would have been much meaner to the neighbor.
Because what the OP did unfortunately didn't work to protect her hens (it's tough to work reasonably with irresponsible dog owners... or, really, with irresponsible people of all stripes), that doesn't mean that I am more reasonable, and it doesn't mean you are. Maybe it would have worked out if I had called the sheriff--then again, maybe the neighbor would have less sympathy for the situation than he already does. We don't know.
So many people have lost chickens on this board, some to predators--canine or otherwise--some to disease or parasite, some to misplaced waterers, some to unknown infections, it is not kind to suggest that simply because someone behaved differently than you would have in a given situation (was or wasn't able to afford a vet, treated with Tylan or another antibiotic, didn't quarantine as long as you would have), that the person's loss should be shunted to the side in order to suggest that the only reasonable response to any given situation is the one you would have had. This is a time for sympathy, and for suggestions for the future.
I think we can agree that purchasing baby chicks and then not knowing enough even to provide food, water and an appropriately heated environment is probably not reasonable. Asking "WHY?!" in that case may be tempting (if not productive). However, trimming wings, speaking to the neighbor and making plans for a more secure run all of an evening... my guess is that seems perfectly reasonable to most people. I'm very sorry it didn't work out.