This is a tough situation but, if the image is really meant more for sentimental value and not so much as a hero image for a client, you can massage it to something acceptable-ish. The shot itself suffers from a few problems, including the focus (the guy on the right of camera is blurred) - the camera probably had some trouble focusing in the harsh backlighting and f/2.8 gives you little room for error or out-of-plane subjects. Next time maybe f/4 at ISO 1600? The noise is what it is, and is not terrible and can be handled in raw conversion. Underexposure is leading to color issues as you boost the shadow tones. And, as pointed out, the lens flaring is causing a blue local cast across the main subject. Fortunately, he is wearing a dark suit and the loss in contrast and the blue cast caused by the flare can be burned down into the suit.
Once you get raw conversion generally done, you can burn locally to balance the suit tones. Then add some local contrast to the faces and hands of the subjects to re-establish form and add some sharpening.
The background is irretrievable and not worth attempting to reconstruct, reshoot. You can burn in the wooden beams in the window to darken them as well if you want.
As you can see, the guy on camera left (cropped out of my posted image) is pretty well-exposed. Next time, try to shift your location to shoot the main subjects without a window behind them, perhaps.
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