Hi

Mandatory requirement for a safety officer after graduation in your case plain BSc is a diploma course in any related field. So you can choose one out of the 2 diploma courses you mentioned above. Nebosh is absolutely worth doing. In few jobs profile i came across it was mentioned as mandatory and in few they were mentioned as an added advantage and also its mandatory if you are applying for jobs abroad as they take more safety precautions than in india. But there are different courses in Nebosh and they are expensive and takes longer duration so choose wisely. Try to gain work experience as early as possible. Work experience will lead you to better job prospects as its safety officer we are talking about and try to get ISO certifications and keep updating your knowledge once you land a job.

If you have any other queries do let me know.

All the best.