Short answers, pulled from the story.
Mahadaji Shinde led the Maratha cavalry force that captured Delhi on the 10th of February 1771. He guided a column of 3,000 horses into the city, ending Rohilla control of the Mughal capital.
Shah Alam II was restored to the throne of Delhi following the Maratha capture of the city in 1771. The Marathas presented nazar to the emperor and formally professed their allegiance after entering the city.
The Maratha chiefs demanded 40 lakhs of rupees, the cession of Meerut and neighboring districts, and the right to appoint all imperial officials below the rank of Wazir. They also required half of those officials' nuar. Saif-ud-din Muhammad Khan accepted these terms on the emperor's behalf and forwarded them for ratification.
Zabita Khan was the Rohilla commander placed in charge of Delhi by the Afghans. He refused to pay nazar to the Maratha representative Visaji Krishna and was expelled from the Maratha camp. His soldiers inside the fort also refused to surrender, forcing the Marathas to breach the ramparts.
In 1772, Shinde and Holkar led a Maratha army of around 50,000 soldiers into Rohilla territory to punish them for their alliance with the Afghans at Panipat. The campaign slaughtered thousands, desecrated the grave of chieftain Najib ad-Dawla, and captured Najibabad. The surviving Rohillas fled to the Terai region.
The Marathas captured Delhi to reverse the Rohilla dominance that followed their defeat at the Third Battle of Panipat. The Peshwa's new instructions ended a passive policy toward the Rohillas, and Mahadji Shinde's campaigns across the north had re-established Maratha authority in the region.