Dear Kelly -
It’s a curious dream, though not too uncommon. I think you may be associating the loss of your grandfather, whom you did not get a chance to “say goodbye” to, with that deepest of all fears of a parent - losing a child. Perhaps the death of your grandfather - and it’s unexpectedness - impressed upon you the fragility of life. By extension, your dream seems to reflect the fear that you could unexpectedly lose your son.
I would hesitate from placing more significance upon the dream than this. I know that a dream like this would rattle any mother’s nerves, especially with your deceased grandfather instructing you to say goodbye to your son because it will be his last visit, but this most likely is just a bit of “dream logic.” In dreams we always try to make sense out of events. For example, your grandfather appears in the dream, who you realize is dead, but instead of recognizing that you are dreaming you understand in the dream that he is an angel. Next, when your son emerges from the pillar, he also is dead. As I mentioned before, this may be a representation of your own, natural fear of losing your son that may have been caused by your grandfather’s sudden death. So your son appears in the dream dead - hence he also is an angel. And you believe this in the dream, rather than protesting that this is not possible - that there is a lack of continuity and of time - and that you just just tucked your son into bed a few hours ago. And then, perhaps because folk lore tells us that angels always visit briefly and then leave, you finish the dream with both “angels” leaving. It is logical in the dream, but it doesn’t fit with your real life at all. Do you see what I mean? This is why we call it “dream logic.”
If there is a lesson to be learned from anyone’s dying suddenly, it surely is that life is precious and mysterious, and that we really want to live each day to the fullest. Because we never know. If this is the lesson your grandfather’s death and this subsequent series of dreams imparts to you, then I applaud it. I would be skeptical of any interpretation of your dream that tries to reach farther than this.