It is true that the angiotension converting enzyme inhibitors (ACE inhibitors) are a
cause for a persistent and annoying cough. The treatment is to stop the offending drug, and use other agents to control the blood pressure. The cough usually disappears sometime after the offending agent is stopped.
If the cough persists, other reasons for it should be considered and perhaps her physician would consider chest x-rays. Symptomatic treatment can be given for persistent cough if it is benign in nature.
Please note that I am unable to diagnose medical conditions online.