Out of your 3 initial candidates, the Dell seems like the nicest to me. However, if she won't be playing games or editing video, I think the discreet graphics card is just going to add unnecessary weight and cost to the laptop.
The i7s are also not worth the additional cost in my opinion. A quad-core i5 (i5-8???U) should be good enough.
Other features I'd want in a laptop:
at least 8GB of memory
FHD (1080p) screen (IPS and touch are also nice to have)
good port selection (both USB-A ports and USB-C)
good build quality
Lenovo Yogas usually get decent reviews, so I'd consider those as well. I have a Dell Latitude 7390 2-in-1, which uses a Yoga-style hinge, and it's sometimes useful for watching video, etc.