Ghost really exist but the aspect where ur friend saw a neighbor is d fact that it is not his or her neighbor that he or she sees because the bible makes us to know that its the living that knows he or she is going to die but for the dead they r conscious of nothing says Ecclesiates 9:5 so where ur friend sees a neighbor it is a demon that is at work , my advice for u to give ur friend is to be very prayerful and draw close to God

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As it is prescribe by d bible, there is pure difference BTW a ghost or spirit and a demon.
Note: I said ghost or spirit and demon
Reason is that ghost is thesame as spirit but where u refer to demon ,then, u r sure of it being an evil spirit but while its a ghost or spirit, it can either be an evil one or the good one.
Back to d topic; if someone is being called back 4rm the dead that is pure spiritism and what appears to u is not d person but an evil spirit posing to b. Even God forbids it (Isaiah 8:19,20 Leviticus19:31)
Fortune tellings is aid by Demons i.e evil spirit check Acts 16:16-18 for more details on demon
The other spirit is the Holy spirit that forsure comes 4rm God, check Acts 2:2-3 and vs 33 of thesame chapter, John 14:17 for now, reply if not satisfied and specify. To God be d Glory