This is exactly why I can't stand Halloween. Why do we want to put all of this in our kids' faces? What do your neighbors think is good for kids in their decorations? Why would a school host a haunted house?
Instead, apologize to your daughter that she had to see all of that stuff. Instead of telling her that it is all make-believe, tell her how hard it must be for her to have to see all of that stuff. Her fears are real and not make-believe. Ask her what she thinks about as her imagination takes off. Have her tell you what is the most scary part of it. Help her to see that you believe that her fears are very real. Tell her that you did not realize how scary this was for her and that you will protect her from such evil-looking images in the future. Explain that some people like to be scared as it gets their heart pumping or something, but it is very normal that she didn't like it and you are glad that you know that now.
Then reassure her that you and your husband will also protect her from anything that could possibly harm her. Give her examples, like how your husband is strong and would never let anyone get near her, especially at night. Tell her that you never hear of any stories on the news of anyone getting into someone's house that was locked. Show her that you lock all the doors at night and she is safe. If you have a bible, show her verses in the bible that remind us of God's protection. (You can google "God will protect" or "angels will protect" to find the verses.) And you can even get silly and tell her how you would run and scream after anyone that would come near you, and throw your heavy purse at them, for example.
Then tell her that if she is in her bed, she can call out to you at any time and you will come in and check on her.