My grownup son will be in Vienna in July for 1 day, that's how his flights worked out. He arrives at 7 am on Thursday and leaves 10 am the next day.
His interests are history, art, museums, local food.

I am looking for suggestions how to spend 1 day in Vienna.

Considering that he has limited time does it make sense to take a group tour for an overview in the morning, have lunch in one of the cafes, spend afternoon in the museum(s), evening - either dinner or music concert or both.
Can someone recommend a good small group tour in Vienna? As for museums - Belvedere or Habsburgs Treasures?
Any suggestions for food place

Lots of useful Vienna suggestions on this prior thread, including some of my own
Vienna, Austria for 5 days in early June

Over our time in Vienna (7 years) we had friends passing through for a day or so, and colleagues with but a day to sightsee here. My recommendation has always been to skip a tour and simply focus on one or two places. With an interest in art and history, perhaps the War History Museum in the morning; lunch at Plachutta (classic Viennese); a walkabout the Inner Stadt to see Stephansdom and Peterskirche; coffee and torte at wherever there might be a shaded outdoor table for people-watching; and then head to KHM for art. On Thursdays KHM is open late, so perhaps make a reservation nearby at Burg Ring 1 (updated Viennese) for dinner.

Just my €0,02.

Can you suggest a taxi service from the airport to Vienna and back to Airport my plan its also to visit Vienna on one day.