If the intended subject of the scene is that the little boy has just died, then you need to light-balance the various portions of the shot (probably by compositing each one of them separately). The actor who’s getting the short-shrift right now is the grieving parent, who is almost invisible. The back of this character’s clothing is dark.
I would also seriously reconsider the sculpting of the boy’s face. The eyes are noticeably unrealistic and perhaps should not be open.
The emerging spirit (especially, because of visual interference with the face) ought to be desaturated and somewhat translucent. The angel must also be, and perhaps his/her color should be a little more golden.
There are lots of opportunities for adding additional colors to, for example, the apparition of the boy’s spirit. The overall effect here is good but somewhat one-dimensional. You can get a lot of good out of layering slightly-offset images of the same shot, with different color-casts and transparency, to add volume.
You need to be very careful that the angel doesn’t look like a flat photograph that you grabbed from a story-book somewhere and pasted over the top of it.
You really need to be sure that the viewer’s eye registers three things: the grieving parent, the boy’s face, and the flatline monitor (which is in a very peculiar position given actual medical practice). Right now the eye “hits” either the angel or the spirit first; has to dig through light to get to the boy’s face; doesn’t really see the opaque-shadow parent at all; and might not observe the monitor due to its peculiar position for quite some time.
I don’t think you need to do much at all with the hospital background, particularly if you have separated the shot into enough “comp” layers. Perhaps you can simply adjust the color and saturation levels of those layers without burning more render time. You don’t want the darkened room to be pulling the viewer’s attention away.