BMM

There is no particular text book or coaching classes for the B. M. entrance exam. So, there is nothing as such you have to specifically prepare for and the paper pattern, type of questions change from year to year. But here are a few things you can do and should keep in mind. Firstly, read the newspaper daily! Gather some general knowledge, be aware of the current affairs, reading magazines and periodicals might help too. Read everything possible. Go through some brands, their case studies etc. Further start writing about anything and everything you can imagine. Be it a hill station from a hawks point of view or the world from a 2 year old kids/ a puppys point of view. Choose any topic randomly and write such that you can write around 1000 words or maybe just 200 words on the same topic. Boost your imagination, think outside the box, don't use clichs or jargons. Be simple and to the point. Basic mathematics is important too. They asked a few sums on calculating the volume of a box during my entrance. Be familiar with brand/ organizations/ movements and their logos too. It will be a plus point if your good with drawing (you don't need to be Picasso) just basic drawing skills are more than enough. If your bad at drawing but have a creative mind, an imaginative brain the drawing section is the perfect chance to showcase your imagination skills. The interview might be a bit intimidating (it was very for me) but just relax and stay confident. So that's all! Don't worry. Stay focused. Stay calm and your done. Everything will be awesome!
Hope this helps!

As per UGC NET 2019 Eligibility you are not eligible on the basis of B. M. degree only. The detailed eligibility criteria is as under.
1. Age:- He/ she must not be more than 28 years as on January 1, 2019 for applying for Junior Research Fellowship. A relaxation of up to 5 years is provided for candidates belonging to reserved categories.
2. Academic Qualification :- For candidates who wish to appear for NET 2019 conducted by UGC, they must clear all the defined standards. Given below is the eligibility criteria to appear for NTA UGC NET 2019:
Candidate must have scored at least 55% aggregate marks (50% for SC/ST, OBC- NCL, PwD) in Masters Degree or equivalent examination from university recognised by UGC in Humanities (including languages) and Social Science, Computer Science and Applications, Electronic Science etc. To be eligible for UGC NET 2019. Candidates who are presently in the final year of their Masters programme or those who are waiting for their final year results can appear for UGC NET 2019 test.