is ISBM gurgaon, inmantec ghaziabad, are good institute for mgmt studies??

I feel you should try for colleges who provide practical knowledge as well like The Delhi School of Communication(www.dsc.edu.in), SIBM(www.sibm.edu)... These colleges have good placements.. All the best

The college which gives good placement opprotunity is I believe a good institution and INMANTEC masters in this.

Yes, they are.