The theme of "Haunted Houses" by Henry Wadsworth Longfellow is:
"Ghosts are nothing more than Memories".
The poem gently draws a parallel between memories and ghosts. Hence, an appropriate them would be:
"Ghosts are nothing more than Memories"
In his opening lines, he defines what a haunted house is:
"All houses wherein men have lived and died
Are haunted houses."
Notice the similie; a comparison between ghosts and memories when he states:
"the illuminated hall
Is thronged with quiet, inoffensive ghosts,
As silent as the pictures on the wall."
Hence the theme: Ghosts are memories.
Learn more about themes in the link below:
https://brainly.com/question/26831613