The easiest way to make the items snap back is to do this:
- Set the Drap & Drop Options to "Return item to start point if dropped outside a correct drop target."
- Delete the triggers that change the wrong items to the DropIncorrect state.
Another option is to add a 0-length motion path to the objects. Trigger that move to happen when the object is dropped on the House Target. I included that, because using a 0-length motion path is also how to trigger incorrectly dropped objects to return when they've been evaluated as wrong and you're giving the user another attempt.
Both options are demonstrated in the attached file.
BTW, making the wrong objects snap back means the user can never answer the question incorrectly. Thus, there's no need to provide multiple attempts.