Priya alias Shivani's body was found Wednesday in a compartment in the bus meant to store a spare wheel.
Police Commissioner Alok Mittal identified her father as Sanjay and the cousin as Ameen alias Chiku.
They were arrested Friday on the basis of technical evidence. They will be produced in a court Saturday, Mittal said.
"Priya was having an affair with a man and had eloped with him a few months ago," a senior police officer told IANS.
The family traced her and sent her to a relative's house in a Gurgaon village.
Priya's family belongs to Dhanora village in Mahendergarh district of Haryana.
On the midnight of Wednesday, she was heard talking on her mobile telephone by her father, said police.
The furious father and the cousin then consumed liquor and decided to kill Priya to save the family's "honour".
They first beat her. She escaped and hid inside the school bus parked near their house. The father and cousin strangled her and hid the body, the commissioner said.
The accused tried to misguide the police saying Priya's lover might have murdered her.
--IANS (Posted on 23-08-2013)