I will be completing my B.Com honors in June 2018. Will it be difficult to pursue Masters in mass communication?

Yes, you can pursue, but you need to know the basics of mass communication to pursue Master's degree.

You can pursue Masters in mass comm. but it will be a change of field. Some alternate options related to your field are: Students who have successfully completed B.Com honors can go for many higher level courses. As to join courses like MBA, MCA, LLB, etc, candidates will have to appear and qualify