Mass Communication & Media

It depends on many factors your finance, you marks and in which university you will be comfortable. If you want college in Bihar, there are many colleges. Go online and see the ratings of college, it is better to know about anything aggregately in comparison to individually.

Yes, you can do event management after B.Com. You can go for a proper degree or else even Diploma degree will do.
For diploma, usually there's nothing such to clear for application, but in some there is basic entrance examination.

For this, you can do a Bachelor's degree or even Master's degree on film production and all. Look for colleges which provide you with editing and stuff.

Yes, you may apply for mass communication after 12th if it's your desired field but you have to get at least above 55% in your class 12th board that too with English as one of the best four subjects.

Please refer to the link provided below for a list of colleges which offer courses in mass communication and journalism in Mumbai. You should be able to navigate to a college of your choice using the filters on the webpage. Important details like fee structures, affiliations and recognition, brochures are available at the link provided below:
https://www.shiksha.com/mass-communication-media/colleges/colleges-mumbai

You may join an MBA in event management course.

Yes, the course includes the topics that you have mentioned. for the current course syllabus please refer:
https://christuniversity.in/humanities-and-social-sciences/business-studies-and-social-sciences/ba-hj/syllabus/404/2017
And for more information regarding the course refer to https://christuniversity.in/humanities-and-social-sciences/business-studies-and-social-sciences/ba-hj