Hello KK,
Thank you for asking at HCM.
I went through your wife's history and I would like make suggestions to her as follows:
1. For 
sun allergy, I guess she has redness/hives with itching on parts exposed to sun. This is known as solar 
urticaria. I usually advise such patients when they come to my clinic:
a. Take an antihiatmine like cetirizine/levocetirizine/
hydroxyzine when having symptoms. 
b. Apply sunscreen cream/lotion with sulnight protection factor (SPF) 15 or more when exposure to sunlight is anticipated.
c. Cover exposed parts of the body while moving into sunlight.
d. Take diet rich in vitamins & minerals (especially 
vitamin A and 
retinoids - carrots, spinach, milk & dairy products, green leafy vegetables, most "yellow" colored fruits like mango, etc).
e. Avoid activities causing 
excessive sweating and too hot/spicy foods.
2. For allergy to kumkuma, I would suggest as follows:
a. Avoid applying kumkuma till healing of the skin, if possible. If not possible, I would suggest to change brand/source of the kumkuma so that some of the ingredients can be changed.
b. I usually suggest application of lotion such as calamine over the area of 
skin allergy. If this does not cause improvement, corticosteroid skin creams may be applied under guidance of a dermatologist/allergist.
Hope above suggestions will be helpful to her.
Should you have any further query, please feel free to ask at HCM.
Wish her the best of the health.
Thank you & Regards.