If her eyes itch ask her doctor for a prescription for Patanol Eye Drops.
Allergies are an immune system problem, and can be very difficult to treat. This is a problem of an overactive immune system that is treating non-harmful materials as harmful. One way to deal with it is to try an elimination diet, where you get rid of most everything you eat and slowly add in foods one at a time, since food allergies are quite common. Certain foods will also make allergies worse by increasing inflammation -- most common are wheat, dairy, and sugar, but anyone can have food intolerances to just about anything. Keeping the immune system in check might also be helpful -- a product called Moducare can help with this, but don't expect a cure from it. Homeopathy is helpful to some, and some chiropractors claim to be good at aiding allergy sufferers through muscle testing. Many medications aggravate or cause allergies either directly, or by impeding the immune system. Then there are the multiple toxins in the environment, including in the home, that can be the problem, such as mold or food additives such as MSG and soy derivatives if one is allergic to soy, a common allergen, or corn additives, another common allergen -- these are omnipresent in processed food in the supermarket and as fillers and binders in pills. Some people are just allergic to certain geographical areas -- I live near DC, which is for some reason just a horrible place for people prone to allergies. Good luck.
Beat Spring Allergies with Bacteria