Seeking ID of book of Halloween ghost stories

[bluetomb]

Morning all!

Had an enquiry at my work which might ring a bell with someone or other here. Book of Halloween ghost stories, thought to have been published in the 70's, dark blue cover with a picture of a grey haired man recoiling from the ghost of a mongoose. One story about a girl having a Halloween party and talking to another girl in the mirror who turns out to be a ghost, another story about some children who get lost in an old building and are helped out down a staircase by the ghost of their mother. The enquirer doesn't remember the title, editor, publisher or anything else. I presume the ghost mongoose (Gef or a friend?) figures in one of the stories as well.

Thanks for any help, much as I enjoy trawling old anthology covers online instead of more serious work.