Both destinations are served by Dehra Dun (DED). Since there's no flight route between them, the best way to travel is by road.
Dehradun
Fly to Dehra Dun (DED), then travel by road to Dehradun. Taxis, buses, and private cabs are available from the airport.
Auli Uttarakhand
Fly to Dehra Dun (DED), then travel by road to Auli Uttarakhand. Local transport options include taxis, auto-rickshaws, and state buses.