Need to show Data in excel format using c#, Asp.net.

Well, you will have to write custom logic to generate such excel sheet. Pick col span 2 as header and then filter records based on Deck = 'A' , Deck = 'B' and so on. Write to each cell value based on header (H1/ H2/ H3...) and Deck (A/ B/C ..).

 

https://blog.e-zest.com/how-to-generate-the-dynamic-spreadsheet-in-dotnet