Looking for a book I read as a child

[Astha]

I've been searching for a book I read as a child. In 1998 maybe, not very sure. But I can't find it anywhere. It's about a bunch of kids on vacation to the countryside where they unintentionally break open a witch's grave. The ghost begins to haunt them and the ghost of her twin sister is trying to protect them. It's silly but just wanted to find out the name. I remember one more thing, the book had the face of a laughing woman half of which was a skeleton
Can anyone help me out?