This is actually a great suggestion. If you are a dog person it can bring a lot of joy, amusement and companionship. The thing that sucks though is that they very short lives. My lhasa apso did live to be 17 years, but this is unusual for most other dog breeds.
About loneliness and losing people dear, my brother's friend's dad lost his parents, wife and son all at an unusually early age. I would have no idea how to deal with that.
Part of my commute involves walking through a public park and I've noticed that the people out walking their dogs seem to find it much easier to strike-up conversations with each other thank other park users. I'm not a dog person, but a dog might help Xcelerate's father make new friends, or at least acquaintances, as well as providing companionship.
I also agree with this suggestion. I know that battle grounds are drawn on the dog vs cat debate, but either/or would do well for most lonely people. My wife's grandfather died when we first started seeing each other; 5/6 or so (oops - I hope she isn't reading) years ago. Bizarrely, this was within a few months of his dog dying. He took that thing everywhere - snook him into hotel rooms, family houses, the golf club, trips abroad.
About loneliness and losing people dear, my brother's friend's dad lost his parents, wife and son all at an unusually early age. I would have no idea how to deal with that.