6 Zone Panel with Keyfob

I fitted a 6 zone panel to a set of stables 30 years ago when my daughter had a pony, as fate would have it my daughter is back at the same stable with her horse & our grandchildren's pony. The lady who still owns it is now in her 80's & is having difficulties using the keypad so I'm looking for the cheapest alternative that would give us key fobs to make it easier for her. Ideally it would also be compatible with the existing Honeywell AG6 bell boxes as we need to do this as cheaply as possible.