IAH to QRO
[f you get lucky and QRO leaves from E it is right there or you can skytram it over to C in 5 minutes or walk in 15 presuming a normal walking speed and no injuries, wheelchair and such.]
UA QRO flights are scattered all over C, E, and occasionally D. E and D are easy.
I think high number C gates are more quickly accessed by walking from the arrival hall. Low number by Skytram.
Skytrams run every few minutes but have are extremely crowded these days. With road construction on the airport, and Terminal E checkin shut down, many people are arriving and going through security at A or B, then tramming to C/E gates.
Hopefully, the travelers will be sitting near front of plane and can walk well. If the arriving plane is on time, they should be okay.
They should keep in mind that the 1:54 connecting time is actually considerably shorter than that. It can take ten minutes or more to get off the arrival plane. And the gates for the departure will close at least ten minutes before pushback. So, consider it about 90 minutes.