I'm talking outta my ass here, but this episode felt like Yachiyo coming to terms with humanity's death, and her own mortality. She witnessed the graveyard of humanity, indulged in human merryments one more time, and ultimately discarded all of it. At the same time, it's pretty obvious that Yachiyo herself won't live forever, and she knows it. Ultimately, Hotel Gingarou must outlive her and be inherited by Ponko's family.