not sure if this is the right place .. but anyway

My head is a mess, sorry ladies. Will try to be short and clear. Son aged 55 is estranged from us, started many years ago when he met a new partner. She died 3 years ago and he's been depressed ever since. House is a mess, he is a mess, council and job centre keep finding him jobs and he keeps taking days off then loses the job. Too long a story really so cutting it all short there. Now off work through mental health issues, not spoken to me for a year, and only texts his dad occasionally to beg for money. Lately we've been worried without knowing anything concrete, just feeling concerned. I tried to call him but the phone is off, gone.
Finally tonight I got in touch with his one and only friend left from the old days, who scared me stiff. He says Kevin was recently in hospital with (his third) bout of pneumonia. Got home and when his friend visited him he could hardly get out of bed, was "puffing and wheezing and gasping like an old old man " and looked terrible. That was 2 weeks ago. He had no money and no food apart from a bag the food bank left on his door once a week. I'm now terrified he is lying dead in that house. None of the neighbours know how to contact us, we live miles away and my husband is 80 and ill, waiting for a heart valve op. I dont know if he is fit to drive all that distance to check Kevin is ok, but I think we're going first thing tomorrow anyway.
Not sure what I'm asking here, just needed somebody to explain things to. His brother and sister have both disowned him long ago -he is aggressive with all of us apart from his dad- so I can't talk it over with them. I'm just so lost here. And sorry to go on and on. I think what I need to know is who could we approach for solid practical help to keep him alive and well. He is in a private let with a good landlord but if they see that state of that place they will heave him out on the street very fast. Then I could get him to go homeless down here nearer us (but not too near). I just don't know how or where to start, really.