Immediately after death, a spirit will often stay around earth. Why?

 Spirits often think they are still alive after death.  A spirit guide may need to show a spirit their funeral or earthly body as verification that they are deceased.  The spirit may be confused, and keep their earth bound connections, leading them to visit their homes and their loved ones instead of progressing.

(The questions below are from The Spirits Book: Modern English Edition, Allan Kardec pg. 154, 2003)

- Question 327: Do spirits ever attend their own funerals? Answer: Very often. But in cases where they are still in the state of bewilderment that follows death, they do not understand what is going on.

- Question 328: Is a spirit ever present at meetings of its heirs? Answer: Almost always. Providence offers such occasions as learning experiences and for the spirit to reassess its views. The spirit is able then to determine what the declarations of affection and devotion it heard during life were really worthwhile.

(The statements below are from Journey of Souls: Case Studies of Life Between Lives, Michael Newton, pg. 13, 1996 and Destiny of Souls, Michael Newton pg. 1, 2003)

- ...souls often have little interest in what happens to their bodies once they are physically dead...because they do not realize that they are dead.  Souls want to hover around the place where they died for a few Earth days, usually until after their funerals, as a way to see their body and know they have died.

- ...there is one basic reason for many spirits not wanting to immediately leave the place of their physical death. This comes from a desire to mentally reach out to before progressing further into the spirit world.

- There are souls who choose to remain at the scene of their death for a while. Discarnates who choose to comfort someone who is grieving, or have other reasons to stay near the place of their death for a while, experience no sense of time loss.

(The statement below is from Here and Hereafter, Anthony Borgia Chapter 1, 1968)

- The spirit body may take some days of your time before it becomes completely separated from the earthly body, and it may be hindered very much by the combined thoughts of the sorrowers who are participants in the dismal rites. Instead of departing from the earthly sphere, the discarnate one will be attracted to the scene of obsequious activities, and more than likely will be saddened himself by what he is witnessing and by the sorrow of those he has left behind. He will feel a heavy weight within him of the separation that has come about, and perhaps being ignorant of what has befallen him, he will be doubly distressed, and even terribly distressed by the fact that he speaks to his friends but they cannot hear him. And how great a difference a little knowledge would make!