The old lady insisted on coming along.
Shen Lan's case involved "deliberate injury," and the victim's family was difficult to deal with. Cheng Yanqing really didn't want the old lady to take a trip too.
"Grandma, why don't you stay at home to prepare dinner? Rest assured, I will definitely bring Shen Lan back safely," he proposed.
The old lady, stern-faced, refused. "Cheng Yanqing, do you think I'm that fragile?"
"Are you taking me or am I going myself?"
The old lady gave Cheng Yanqing a choice.
The former would allow him to personally accompany her, which was reassuring.
The latter would leave the old lady unsupervised and expose her to potential risks.
Cheng Yanqing had to compromise.