Dear Vipul1711, First you must realize that the cost of treatment has nothing to do with the outcome. As long as appropriate treatment is given the outcome will be as expected. From what you have mentioned, it seems your mother might be suffering from Angle Closure Glaucoma
which can be treated by Laser
and cost of treatment quoted by your doctor seems to be reasonable. Also the cost will vary from doctor to doctor and place to place. So do not worry and follow your doctor's advice.