In Vampire Knight what does I'll also show you a sweet dream next night mean?

It means there will be a next episode or in the next episode you there will be exciting things approaching.

If you watch the last episode of vampire knight guilty you notice that the saying is not shown.

Its not that that is a metaphor or a hint to show you that all of that happened before Yuki Cross gt changed in to YUUKI KURAN was an air buble or in other Words a sweet dream. Because that was not her real self it was a FANTASY.