National Institute of Design, Ahmedabad Eligibility

Yes B.Com graduate can apply for M.Des programs for NID.

Yes you are eligible. The eligibility criteria of B.Des. of NID for Product Design is given below. Eligibility criteria : 10+2 in any streams or AICTE approved three-year Full time Diploma after Class X offered by Board of Technical Education of any state in India or Union Territories. 

B.Des in Fashion Design is a 4-year undergraduate course, the minimum eligibility for which is a Higher Secondary Certificate (10+2) qualification with a minimum aggregate score of 50%. The programme is spread over 8 semesters, with the final semester being based on the candidate's chosen stream of study.

For B. Des - 10+2 in any stream from any recognised board
For M.Des - Bachelor's degree of 4 years duration.

Yes, you can go for NID. Stream does not matter in UG. Application is out for the entrance session 18-19.

You can refer to the below link for eligibility at NID based on the course you are interested.
https://www.shiksha.com/college/national-institute-of-design-ahmedabad-paldi-33410