Grandpa's visit to Beijing was like a bolt from the blue to Jiang Ni.
When she first returned to the country, she did so under the guise of a graduation trip. Grandpa had no idea of her real intentions. Had he known what she was up to, he would have done everything in his power to stop her and never would have let her return to Beijing.
Because Jiang Cheng had refused to leave the Jiang Family, Grandpa had pretty much cut off relations with him. For many years, whenever Jiang Cheng went abroad to visit Grandpa, he was met with a closed door. Grandpa had always turned a deaf ear to anything related to the Jiang Family, even to matters concerning Beijing.
This time, with the significant trouble Jiang Cheng had gotten into, Grandpa must have heard about it early on, yet he never planned to intervene. That's why from the beginning, she never thought about asking Grandpa for help and decided to return to Beijing on her own to try and solve Jiang Cheng's problems.