re: Camera Recommendations

Looking at the D50, you'd have to stick with a DX format (APS-C) F-Mount body from Nikon to reuse the lenses (or go with something like MFT with an adapter/speedbooster), unless she already has FX lenses.  The newer higher end Nikon cameras are going to a different lens mount, but I believe the most current F-Mount are the D3500, D5600, D7500, and D500 in cheapest to most expensive.  There's a decent jump from 5600 to 7500, and even bigger jump to D500. 

I've got a D5300 that I've had for about 10 years, and other than not being able to shoot 4k video I've been quite pleased with it.  It offers enough controls to keep me happy when I want to, and the 5000 series has a better autofocus than the 3000 series, so I'd say that jump is definitely worth it, but the jump to the 7000 series or 500 is a matter of preference, in my opinion.