Hello Aspirant,

In order to prepare for Mathematical Physics for IIT JAM :

• Schaum's Outlines series
  Mathematical Methods for Physics & Engineering: Riley, Hobson & Bence

is one of the highly recommended books.

However, since it is very lengthy in nature, it is suggested to read the topics individually from the books by the following authors

• Vector analysis and Fourier analysis:  M.R. SPEIGAL
• Differential equations:  KREZIG is the author recommended for theory and H.K. DASS is the author recommended for problems.

However, if you only want to buy one book, then

• Schaum's Outlines series
  Mathematical Methods for Physics & Engineering: Riley, Hobson & Bence

is a good choice.

Thank you.