I'm only 5'1" myself and other than my custom 650c wheeled road bike, I ride 24" wheeled juvenile bikes when it comes to "off the shelf" bikes.

Try Giant, https://www.giant-bicycles.com/us/bi...ears--24-inch-
I personally ride an ARX24 which I have modified a bit for better fit but the fundamentals are there. The Escape Jr 24 may work quite well for your wife right out of the box.