hey pradnya

yes you can also score good marks in NEET without taking a drop year . it depends upon you dedication and hard work . you shoul start preparing early (from 11th) and be consistent in your studies . you can give the neet exam just after your boards and it doesnot recquires undergraduation to appear in NEET exams .check out this also 

https://medicine.careers360.com/tags/how-prepare-for-neet-0

best of luck