please advise - 2 persons age about 80 years old go to jiuzhaigou

To be honest, senior people over 80 years old are not suggested to go to the valley. The living condition there is not pretty well and the bus duration from Chengdu to the valley takes around 8 to 9 hours. Besides, the altitude is a little bit high for the valley, so seniors may feel uncomfortable.

Maybe you can communicate with the seniors to tell them the real situation and try to cancel their trip to the valley.