Hi Ritu,
Salary hike can be made on different basis. e.g. based on past perfoprmence or annual salary increment as per company's policy but irrespective of that hike is generally done for future salary. So if a person gets 16% increment and if we assume his salary is INR1,00,000 p.a then revised salary will be INR 1,16,000 p.a and monthly INR 1,16,000/12.
I don't think for how many months he is working is at all important for calculation of revised salary unless otherwise specified.
Regards,
Sanjay