You can choose various subjects to study after studying Biology in +2. If you are interested in the Medical field, then you can choose MBBS, BDS, B.Sc. Nursing, BAMS, etc. If you are not interested in pure medicine then you can choose paramedical courses which may be BPH, BPT, B. Pharm., BMLT, etc. Other courses for Biology group can be B.Sc. in Zoology, Botany, Geology, Meteorology, Microbiology, Agriculture, Forestry, Environment Science, Veterinary, CSIT, etc. All these subjects have a good scope. It depends on your interest which one would you choose.
B.Sc. Microbiology and BMLT both are lab-oriented courses but Microbiology is a bit diverse field and BMLT has conversed to only the medical laboratory. The scope of both these subjects is very good both in Nepal and abroad. As I have mentioned before it depends all upon your interest and career approach.