Capital gain

YES

 

exemptions rules has been changed from financial year 2017-18...for claiming exemption u/s 10(38) your father must has bought these shares from recognised stock exchange i.e STT paid.then you will get exemption.
for transfer between mr B and his friend if it is from recognised stock exchange i.e STT paid then it is exempt but it should be LTCG.if short term then fully taxable no exemption