First thing was to use the white dropper in levels to set the white reference point on Gramps' shirt. That helped with the colors a little but still needed work.
Next I used iCorrect filter to try to get the skin tones closer to normal. That improved a little but still needed work.
Changed hue/saturation several times to get the skin colors right. I figured if I got the skin right, the others would follow.
Along the way I adjusted levels, curves, and did screen layers with layer masks to bring up lightness of various spots like the suits and their eye areas. Also did multiply with layer masks to improve saturation in certain areas.
Clone and healing brushes to eliminate splotches on their faces, cloned to get rid of the darkened border.
Dust & Scratches, flattened and resized.