Before doing this, why not make her go through youtube vids? Don't look at it like a course, just that she would understand some points and try these on the existing camera/camera app. It would also make her appreciative of DSLRs when compared to the limited feature set of the existing camera.
lens choice highly depends on what type of photography you want to get in. Travel photography usually requires wide angle lenses if you want to take photos in tight streets and of buildings and mountain vistas. using a 70-300 would actually be counter productive. its a good idea to invest in fast lenses. like the canon nifty fifty 50mm 1.8.
Raw image processing will help a lot in creating stunning photographs, invest in a good image edititing software. I use DxO OpticsPro.
I would not suggest canon/nikon cameras. go for mirrorless. There are many options for lenses when you go for mirrorless cameras.