Most light- to medium-roasts approach 150mg/250mL. The one I’m baselining is Dunkin Donuts, the most popular coffee in the US. A standard Large Iced has almost 400mg of caffeine. You can order it with a shot of espresso, if you like.
We have to remember that the drink she was consuming (multiple times) was a 30oz. There are very few coffees with less than 350-400mg of caffeine in a 24oz size (or smaller)