This seems to be Chapter 16 of Harry Potter and the Sword of the Hero by joe6991:
Mrs. Granger nodded and Hermione smiled sadly, but encouragingly at him. Grandma Granger, the squib turned Muggle, just nodded. "So... what are we all up to today?" asked Harry as he took some toast from the rack.
"Well I'm driving mum to the station at ten thirty, and then Janet and I have to be at the practice until late, so its work all day for us," sighed Mr. Granger, rubbing his eyes with his hand.
"We can go to the station to see Grandma off," said Hermione, "but we'll have to catch the bus home. Mum and Dad will be late if they have to drop us back here."
The bus was falling fast now and Harry barely shouted his charm before it was too late.
"WINGARDIUM LEVIOSA!" he cried with every ounce of his being.
The bus was four-feet above his head, and about ten-feet above the road, when it came to a sudden, floating stop. Harry's eye's widened at the sight of it. The bus had fallen on its side, so its occupants were pressed against the pane-glass windows. Harry could see the terrified Muggles and he also saw Ron holding onto Hermione at the back, who wasn't
moving. They were both pressed against the glass.
All of this happened in a single moment, though, and Harry collapsed to his knees almost instantly as the strength and magic required to levitate the bus on his own was tremendous.