Hey Swathi, Glad to know that you want to join civil services so best way is to choose Arts group in 11th standard.So that you can focus in a unidirectional way towards your goal. The subjects you should choose to pursue your goals are:

English

History 

Political Science

Economics

Public Administration 

This will be more beneficial if you are interested in the subjects of Social Studies 

if you have any doubts, feel free to ask.....