I have to think that, in general, 2 people would be more likely than 1 if a possibly unconscious or disabled Nancy was carried from her house and to a vehicle. If Nancy wasn't walking out herself, but was being carried out, that could explain the blood spatter. Whoever was carrying her out may have taken little care to prevent impacts to her body as she was being removed from the house.
It would be difficult for 1 person to carry her out - she's probably at least 100 pounds, probably more - and then get her into a vehicle. It is possible for 1 strong, likely male individual, but awkward. Doors need to be opened and closed. It could be done, but with 2 people it would much quicker and easier.
I lean against this being a real kidnapping. I think there was some kind of family dispute over money or inheritance, and violence occurred.
It's my opinion that Nancy is no longer alive, and that the kidnapping is some kind of hoax.