hey ayush das,she used Cengage BM SHARMA FOR JEE ADVANCED apart from her allen modules.She too solved previoua iit papers. Actually she studied in Srg batch whose question is very upto mark of advanced level so she has a very high confidence for solving very difficult problems. For organic she followed solomons and ms chauhan and allen modules and class notes. For biology part ncert class notes , modules will suffice as per her.She led more emphasis on theory part rather than question solving in biology.

Actuqlly every topper has his/her own strategy, make your own strategy follow it.Success will follow you, very good luck