B.Sc

You should check with the placement cell in your institute if you qualify for campus placements. Many institutes have rules like no backlogs, a minimum CGPA to qualify for placements. Once you clear these basic requirements you should be able to sit for placements.

To get into defence you need to appear for the CDS exam and to get into the the civil services you need to clear the UPSC exams. For this no specific degree is needed, however, you should choose a degree which will help you with your CDS or UPSC papers. Choosing between B.Sc. and BE, you should opt for one which will help you later when you choose your subjects in the UPSC or CDS.

There are many online websites via which you can access sample papers published by HNBGU in B.Sc. You could also try searching for sample papers on Amazon or Flipkart, although be sure to purchase the books, either Kindle or Paperback much before the exam as you may face problems purchasing these books when you are nearing exam dates, mainly with availability.

Please refer to the link provided below for a list of top colleges via which you can can pursue B.Sc. in Zoology. You should be able to navigate to a college of your choice.
https://www.shiksha.com/science/colleges/b-sc-zoology-colleges-india

As you said that now you are purusing your B.Sc in HM, but you are willing to do MBA in the same field.
As I know, you will get the same results after that also, but if you want, then you can go for M.Sc in HM, or you can do it through distance also.

You just have to qualify GRE, TOEFL, learn basic German language and apply for scholarship form, if you need it.
Well, it is a free advice, you can opt for anywhere 'just believe in yourself & prepare for it'.

Just keep calm, and take career guidance by any an experts. And, just don't worry, because everything happens for the best. It is my experience and not only me, every one knows this.

Please visit naukari.com here you can find job details, but I suggest that you go for M.Sc then you can find a good job easily.
All the best.

Either he may go for a job or higher study. I suggest him to do at least PG. It will give him a great satisfaction and respect in the life then if he wants, the best is to go for Ph.D. If he qualifies JRF, he will get INR 12000-14000 as a research scholarship for a maximum period of 5 years until he completes Ph.D. If he wants to do a job then there are vacancies for Bank PO and Staff Selection Commision, NDA, CDS, but don't go for a private job at this stage.