Complete the friendly ghost's polite midnight invitation to the new homeowners.

"Hello there! _____ join me for a lovely cup of midnight tea in the attic?"

The correct answer is Won't you.

Negative questions starting with Won't you are a wonderfully polite and classic way to offer an invitation or make a suggestion.

Just like with other negative questions, the contraction n't attaches to the modal verb will (creating won't) and comes directly before the subject. "Will not you" is grammatically incorrect because not must follow the subject if it isn't contracted (Will you not...).