You shed a tear for the fallen. It wasn't quite their time, they could've lived a bit longer, but they probably lived all they could.
-Wait a minute, how are there bones here?
Isn't this supposed to be Bys' original corpse? So, if she is a monster, then why are there bones here? For that answer, I point you to the fact that suicide is a dangerous thing.
The rules of monsters are a bit confusing. Sometimes one monster may only live ten years. Others may live millennia. But it has been shown that when monsters die, they turn to ash. What if I told you that is only if they are killed. Time, nature, and by other's hand, monster's bones will wither to ash, marking the killer with their last narcing. However, if a monster kills themself, their bodies, which are mostly made of magic, seem to turn that magic into a viscous liquid known as ichor. Ichor is used in very strong magic spells, but it is important to the rest of the body, that it stops the natural ashing process, so you are left with an actual corpse, and that is why monster autopsies only reveal the obvious.
This knowledge has only just been revealed to monsterkind in the last 6 years because Humans during the war didn't want monsters using their own high-level magic, so they hid the knowledge.