The doctor never told her anything about controlling her diet in that respect. Any advice or information would be greatly appreciated.
Your mother does not need to restrict foods containing iron. She needs to eat foods with iron to maintain her red blood cell hemoglobin which carries oxygen around her body.
Vitamin K is needed for blood clotting and if your mother eats different amounts (high one day and low the next day) of vitamin K, it will be more difficult to regulate her clotting time. Remember that vitamin K is a fat-soluble vitamin so it is stored in your body. If your mother is on Coumadin, she needs to eat enough foods containing vitamin K to meet her RDA (Recommended Dietary Allowance) which is 90 micrograms per day for women 19 to 70+ years of age. See table below for a list of foods with vitamin K.