Is it possible your friend can tag along to the lunch? Graduations are not usually that lone 1.5-2 hours? Maybe she can wait in the car, read a book, a magazine, or watch YouTube videos and then attend the lunch and then that would be less time alone for her.
Unless you feel she would get bored waiting alone in the car. You could also get the name of the school and check the surrounding area. There is always a Starbucks. That way she can sit comfortably and then you can scoop her after the graduation.
I say get her input and blessing and then go for it. Forewarned is for armed. That way she can plan properly. Go get some books from the library or buy some magazines.
