No, you do not need to take an entrance exam in order to be admitted to Reva University's journalism programmes (including the BA in Journalism and Mass Communication). Merit screening determines admission; therefore, your scores on the qualifying exam (10+2 or PUC) are taken into account.
All you have to do is apply online via the university's official website and fulfil the qualifying requirements, which include passing your 10+2 from an accredited board. No entrance exam for Reva University's undergraduate journalism programmes is mentioned.