Hey Athira,

Here are few books suggestion for NIELIT Scientist B Exam:

1. General Awareness by Manohar Panday (Publisher: Arihant)
2. A New Approach to Reasoning Verbal and Non-Verbal by B.S. Sijwali and Indu Sijwali (Publisher: Arihant)
3. A Modern Approach To Verbal and Non-Verbal Reasoning Revised Edition by R.S.Aggarwal (Publisher: S.Chand)
4. Quantitative Aptitude by N.K.Singh (Publisher: Upkar Prakashan)
5. Quantitative Aptitude by R.S.Aggrawal (Publisher: S.Chand Publishing)
6. High School English Grammar & Composition Revised Edition (English) 1st Edition by Wren and Martin

Hope this helped,

Thank You.