If she let it get that large, I am afraid surgery maybe the only option.
to prevent this kindof thing, everybody shoul do a quarterly kidney cleanse
The easiest way to cleanse the kidneys is called the Watermelon cleanse. Those who have diabeties should not use this cleanse. All that you do is sit in a bath filled with water, and eat 20 - 100 kg of watermelon through the entire day. While you continuously eat the melons you continually empty your urinary bladder into the water. By cleansing this way people have dissolved big and smaller stones out of their bodies.
I do this every three months and it has worked very well for me.
http://www.colonzone.org/kidney-cleanse.php