I also like Prudie's answer. The parents are unrealistic to expect that their neighbors are going to cater to the whims of a 5 year old. Sure, she's scared, but instead of teaching her that sometimes we're scared of things that really aren't scary, or that there are ways to deal with our fears, they are teaching her that the world will just remove all potentially frightening things or else they are bad people?
If I were the parent of the 5 year old, I'd validate her fears. Sure, if those goblins, ghosts, and monsters were real, they'd be pretty scary...but they're not real. I'd ask the neighbors if I could take her over (in daylight) without any of the special effects to show her it's all plastic and it's meant to be fun.
And while I agree that it isn't the neighbor's responsibility to educate the child, I think it would be a kind and neighborly of them to at least offer to have her come over and see that the decorations are not going to harm her. If they take a step to help her and the parents understand that they aren't purposely trying to scare anyone, it could go a long way. And if it doesn't, at least they can know that they tried to do the right thing and feel better about not bowing to unrealistic demands.