If Delhi's her final destination :
1. She'll need to go through immigration and "exit" the airport. She'll only be allowed to go through departure gate 3 hrs prior to her scheduled flight.
2. She'll only be allowed one piece of luggage and a carry-on weighing less than 7 kgs (they might not care if it's a tad heavier).
If she's going to have 2 luggages, then this is a no-go, IMO. If she doesn't have much to carry, then you could have your brother pick her up at Delhi Airport.
But all things considered, having your brother receive her at the airport and "re-enter" is too big of a hassle.
Go for Chicago-Middleeast/Istanbul-KTM route (wheelchair).