Which is the best course option for Girls after completion of class XII Exam???

There is no such bar for girls in any field after 12th girls can go in any field of their choice.

One should keep a few things in mind while choosing a career

Choose a career in which your interest lies
Potential and Financial capability

Best courses after XII Science:

Medical Line--
MBBS or Bachelor of Medicine and Bachelor of Surgery
BDS (Bachelor of Dental surgery)
BAMS or Bachelor of Ayurveda medicine and surgery,
Optometrists,
Dental Surgeon,
Pharmacists,
Physician,
Nursing and a lots of others

Engineering line --
Aeronautical
Bio-Medical, Information Technology
Marine
Mechanical
Civil
Electronics and telecommunication and many other.

Forensic Science:
Diploma in Forensic Science (Computer Forensics)
Diploma in Criminology and Forensic Science for Police personnel
Diploma in F/Sciences (Ballistics and Finger Prints)
Diploma in Forensic Science (Cyber Crimes)
B.Sc in Forensic Sciences
B. Sc in Forensic Sciences
B. Sc in Life Science, Chemistry, Forensic Science

Zoology:
B.Science (Hons) in Zoology
B. Sc in Advanced Zoology and Biotechnology
B. Sc in Zoology
B. Sc in Zoology and Animal Biotechnology
B. Science in Aquaculture (Fishery Microbiology)

Biotechnology:
B.E. in Biotechnology
B.Tech (Industrial Biotechnology)
B.Science in Biotechnology
B. Sc in Biotechnology and Bio informatics
Diploma in Biotechnology

Agriculture:
B.Sc (Agriculture Mktg and Business Management)
B. Sc in Crop Physiology
B. Sc in Entomology
B.Sc (Bio-chem and Agricultural Chemistry)
B. Sc in Agronomy
B. Sc in Agricultural Meteorology
B. Sc in Agricultural Biotechnology
B. Sc (Hons) in Agriculture
B. Sc in Agriculture.
B.Science in Agricultural Eco and Farm management
B. Sc in Agricultural Statistics

Geology:
B.Sc (Hons) Geology
B. Science in Geology
PG Diploma in Geology (Ground water)
PG Diploma in Environmental Geology
PG Diploma in Engineering Geology

Textile:
Diploma in Fabrication Tech and Erection Eng
Diploma in Textile Tech
Diploma in Textile Eng
B.E in Man Made Fiber Technology
B.E in Textile Chemistry
B.E in Textile Technology

Microbiology:
Diploma in Clinical Microbiology
Diploma in Industrial Microbiology
Diploma in Clinical Pathology
B.Science (Hons) in Microbiology
B.Science in Microbiology

Food Technology:
B. Sc in Food Processing and Technology
B. Sc in Food Preservation and Processing
B. Sc in Food Processing
B. Sc in Food Storage, Preservation and Food Tech.
B. Sc in Food Technology (Bio-Chemical Engineering)
Diploma in Fish Processing Technology
Diploma in Sugar Technology