What is the best way to get from states to cape town for older couple
Based on your location as eden prairie I would assume you are flying from Minnepolis. If you want just one stop, there are a couple of choices, various combinations of Delta and/or KLM with a connection in either Amsterdam or Atlanta. You might want to ease the transition by going through Amsterdam and spend a day or two there. Or you might just want to do it quickest and go through Atlanta and recover when you get to Cape Town.
When I looked into this but never went, the best (speediest) combinations from MSP were Delta via Atlanta and United via Washington, both single connections.
There are connections via Europe that take a few hours more, using SkyTeam partners.
London: Delta then Virgin Atlantic
Amsterdam: Delta or KLM then KLM
Paris: Delta or Air France then Air France
I flew from the west coast. Turkish airlines nonstop to Istanbul, then Istanbul to Cape Town. It is a long way to travel, but so worth it when you get there!
Have you checked your options on Google Flights? There are only a few options for flights with a single connection, with the fastest taking around 22+ hours. Airlines and connecting airport varies by day and time of day. Pick the one that works for you and book directly with the airline.
Delta has a direct flight from Atlanta to Capetown