Hello Ritika,
For admission in Bsc Home science hons, only the aggregate of best three subjects is counted instead of best four, be it any college, lady Irwin college or Institute of home economics or Bhagini nivedita college.
And as it is only best three, you can definitely leave biology while counting the aggregate of best four.
You can take physics, chemistry or maths or English  and even home science.
I hope this helps.
All the best for the future!!