Best possible scenario for the Vampires is N1 Mark, N2 Turn, N3 Mark. Either Robo or Dupti were turned, and Robo got Witched, so there are still at maximum two Vamps. They can grab their third tonight, but not NK (as the Wolves are extremely likely to block the double-bite).
The worst possible scenario for the Vampires is that each time the Elder has marked a target they've subsequently been NKed or Lynched, and Dupti is the Elder and pretending to be a Fledgling under the guise that he cannot vote.