Bariatric surgery. /mumbai /pune?

Hello, My mother has knee problem. She can't walk for more than 10 mins and she walks being bend towards left side because there's a knee problem in her left leg. She is also overweight and because of knee problems she can't do much kind of physical activities to reduce weight. Doctor suggested that she need to do intense exercises in order to reduce weight and get rid of knee problems but she can't do exercise at all. Doctors suggested to go for bariatric surgery through which excess fat will be removed from her body and her stomach size would also be reduced for diet control. In this way her weight will get reduced and she will be able to do the exercises. Should she go for a bariatric surgery? What would be side effects? What would be the cost for it? Who are the best surgeons available in Indore / Ahmedabad / Vadodara /Mumbai /pune? Thanks Mehul