I have an iPad and a Transormer (android tablet)
As as checking email or getting on the internet, it’s pretty much a wash.
Android is going to be cheaper.
If you wanted to video call, facebook would be pretty easy if you want an iDevice yourself.
I personally find using the Android tab easier to use over all but that is very subjective.
If I were buying a device for an 83 year old, I would also look at notebooks, as eyes get older, the larger screen makes a huge difference.
Tried my daughters Ipad today; one click from desktop screen and new email lists appear. If Android or Fire does that too, it may be a close call.