i wonder if there has been a mix up here regarding exactly what was requested & expected.
you can have 'assisted' passage from the airline which is usually for the less mobile - ie may need someone to push them in a wheelchair, a ride on the golf buggy, platform lift to board aircraft if no airbridge etc. most airlines provide that (or rather the airport!).
as far as what you were expecting (basically for someone to walk through the airport with her until she got on the flight), well apart from the Unaccompanied Minor service which very few charters offer these days, i've never heard of that being an option during my time in the travel industry.