Hannah eventually comes to terms with the fact that she's a ghost. As the ghosts are about to disappear, she requests that Henry (who is tugging between life and death) repeat to Owen, "Tell him I love him. And the rest, well...it's just—" The rest, Flanagan confirmed on Twitter, is just confetti. This is an allusion to Nell's poignant speech to her siblings when they're all together in the very last episode of The Haunting of Hill House: "I loved you completely. And you loved me the same. That's all. The rest is confetti."