Your son is eligible for Delhi Institutional quota and Haryana State quota as well. But Haryana as on 2019 counselling session, had 581 MBBS seats for State Quota. Delhi has 481 MBBS seats. Now both the States might get new Medical Colleges in the coming Academic session. And both the States have the history of highest cut offs due to limited seats. But Delhi tops the list in the cut offs. So Haryana might give him a better shot at a seat.