Headscratchers / GeGeGe no Kitarō

• So, how come Kitaro's mother didn't come back from the dead? Like, Medama-Oyaji came back (as an eyeball but still).
  • In Hakaba, it's shown his mother gave some of her energy to a dying man so he would become a yokai and live. Maybe this little amount of energy is what she would've needed to come back. Eyeball Daddy, meanwhile, never gave anybody his power.
• The 2018 series version of the phantom train story establishes that the vampire plague turned every human and yokai on earth before time traveling shenanigans stopped it from ever starting. Now there’s a lot wrong with this so I’ll just ask the main questions. Like if this whole thing was really that easy to pull off (they literally just turned Nezumi Otoko and set him loose), how haven’t vampires taken over the earth centuries ago? Why didn’t other powerful yokai, including organized groups like the Nurarihyon faction or Backbeard’s court stop them? What did Pii and Monroe expect to eat when everyone on earth is a vampire and therefore has no blood?
  • In order, maybe, since the item vital to turning Nezumi Otoko was Pii's hat, they needed to gather enough spirit energy/yoki/whatever inside the hat before they could start their plan. Alternatively they had other matters to attend. For the spreading, it's not at all that uncommon (i.e. pretty much every single zombie apocalypse work). Given the situation, I guess that Nurarihyon at least would go into hiding with his followers and control things from the shadows and while probably Backbeard would fight these "rivals", at that point it doesn't matter for the heroes. As for the eating blood, maybe the vampires of Pii and Monroe's bloodlines don't need to consume blood or plan to keep a handful of humans as cattle.