Usually, calcaneal spurs are not cause for pains, unless severely inflamed . Also the spur is over heel. You complained of pain in ankle joint. Both are different location. Information provided is not enough to diagnose your mother and treat your mother. Calcaneal spur is not curable with medicine. (Though it doesn't require a cure also).

Nothing serious Slight bone growth Start medicine and soft sleeper use

Its not a serious problem but it cannot be cured with medication