Black Book - Vol. 1 Ch. 3

[MangaDex]

 

[ElP45]

Her little sister might got possessed in the past, and since then she were married, prolly the ghost is gone as well but who knows?

 

[Forkuth]

Her little sister might got possessed in the past, and since then she were married, prolly the ghost is gone as well but who knows?

I doubt the ghost is gone.
Ending leads me to believe the ghost completely took over her body and dispossessed her actual soul which now haunts the older sister.
Thats why she refused to take her hand off the coin because then the ghost would lost the body to the little girl again.