Hello,
Cracked feet is basically due to dry skin or xerosis and may be aggravated by certain causes like prolonged standing, being overweight, open back of shoes or medical causes like diabetes, thyroid disease, psoriasis or eczema.
Soak feet or hands in warm soapy water to soften cracks. Then rub with a pumice stone and apply some moisturizer. During the day, hydrate and protect feet with a protective and moisturizing cream. At night, repair them with creams formulated from glycolic acid—a must for improving skin texture and tone. She can wear socks after applying the cream also. An insole or a heel cup may be used to keep the fat pad from expanding sideways. This is worn in the shoe and can be very effective at prevention.
If still the symptoms do not improve then please get a clinical examination done by a dermatologist
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
I have had good results putting tons of vaseline on my heels and putting socks over it before bed. Also a product called Heel Tastic (got it at walmart). Its by Earth to Skin. This stuff is awesome because it kind of looks like a round deaodarent where u take the top off and appy like u would a deodarent. I HATE touching feet so this is very convienent for me.