Hii

Kindly consider the following books-

• Geography & History: NCERT (Std 6th-12th)
• Politics: M laxmikant
• Economy: NCERT (11th-12th)
• International relations/events/diplomacy: Pratiyogita Darpan, The Hindu
• Science: NCERT (7th-10th), few topics from 11th & 12th
• English:R Gupta CDS book,CDS pathfinder book, Word Power Made Easy : Norman Lewis
• Mathematics: CDS pathfinder book, R.S Aggarwal
• For Previous papers: Disha Publications

All the best.

Firstly I would suggest you for NCERT books, depending upon the optional subject you choose. Some of the books you can prefer for IAS preparation are:

History Of Modern India  Bipan Chandra. (History)
Indias Struggle For Independence  Bipan Chandra. (History)
India's Ancient Past  R.S. Sharma. (History)
History Of Medieval India  Satish Chandra. (History)
The Wonder That Was India  A.L. Bhasham. (Culture)
Indian Art and Culture  Nitin Singhania. (Culture)
Geography of India  Majid Husain. (Geography)
Oxford School Atlas  Oxford. (Geography)
Certificate Physical and Human Geography  Goh Cheng Leong. (Geography)
Indian Polity for Civil Services Examinations  M. Laxmikanth. (Polity)
Indian Economy  Ramesh Singh. (Economy)

Good Luck!