Places for my dad to socialize?

My grandfather was taken to an adult day health center, via a small bus, every weekday for years. It was the best place ever. The people there loved him. There were physical therapists, nutritionists, access to speech therapists, etc. It was a wonderful place that really gave him a lot of joy in the last years of his life. Please look into sending your dad to an adult "daycare"! But avoid calling it "daycare", as it can be really insulting to your father and others who attend it.
As for pricing I dont think insurance will cover it. At least for my grandpa they wouldnt. But I would look around for Senior Centers or Adult "Daycares" and ask them about their pricing and transportation. You might find some place thats just right for you both!
Best of luck!

Some senior centers contract with the local transit agency to provide "small bus" (sometimes a/k/a paratransit) service to pick up elders and return them. The more well organized and well staffed centers are likely to have this.

I just googled Vermillion, SD and found that there is a senior center. You might want to contact them, ask about daily activities, transit, and if they publish a newsletter. My father's senior center creates a very professional newsletter, listing activities and the Meals on Wheels menus for 2 months.

Some activities are free (such as the senior health expos) but others do require payment. E.g., the holiday meals were usually about $8 - $10 for seniors, less I believe for seniors who are members of the center. Holiday bazaars are held and there are some good activities, ones that I would have attended if I had the time.

The VA also has a "friendly visitor" program for veterans.

Does your father have any specific interests such as reading? In our area the libraries in the better managed community have book clubs and special events. Some publish monthly newsletters as well.

Two of them are really fantastic for their music programs. We used to go to both when the Saline Fiddlers played. They're a group of teenagers who play string instruments faster than any professional. It's a really, rousing, foot stomping, high energy event, for free.

Many of the little children love it too. They get up close to the stage/platform and start dancing "to their own beat."

These events were really highlights of the month for Dad and me.

Some churches also have musical programs in the summer. Usually they're outdoors though, so seating might be a problem. And that raises another issue - can the aide play CDs for him? It's not necessarily companionship, but music certainly can raise a person's spirits.

Yes, there is adult day care but I don't know very much about payment arrangements. Try googling and adding your Dad's zip code to see what comes up. You might also call the county office of aging where he lives to see what services are available in his area.
You might also try the Visiting Nurse's Assoc. Mine is quite large and they have volunteer visitors to homebound folks. As does my church.