Some questions/theories about the 2nd Ghostly encounter

What had I seen?

To keep this discussion simple, I suspect it might have been:
1) A ghost
2) A Thought-Form

Could it have been a human ghost? Perhaps.

At that time, I felt it was strange for a ghost to be eating ice-cream as it has been said that ghosts do not need to eat the way humans do. I also felt it was strange that ghosts need to wear spectacles and wear clothes.

Was it a Thought-Form? Perhaps.

Because, on the night before that encounter (or perhaps a few nights before), my father had taken me out for a dinner with a student (or ex-student) of his. That ghostly apparition I saw remarkably resembles the physical features of this ex-student (for example, the face of the ghostly apparition does look like the face of my father's student)

I also thought at that time that maybe my father's student had suddenly passed away and had come to visit me. But I found this idea to be strange too as this person was in no way (as far as I know) related to me (I only met him once and he is certainly not a friend. At most he is an acquaintance. From what I know, he is also not a relative of mine).

I am not going to discuss other theories here. One example is the theory that this student of his knew how to astrally project himself and was thus able to visit me in some kind of astral form. (I have since discovered that this might be possible)