How Can Severe Chesty Cough While Having Pulmonary Hypertension Be Treated?

My mother is in the final stages of pulmonary hypertension a complication of her CHD. She was discharged from the hospital a week ago into hospice care and told the family to expect her to live no more than a couple of weeks. She has rallied somewhat. She is responsive and her breathing has eased. However, this mucus producing cough, a symptom of the hypertension I am assuming as she has widespread edema, is taking its toll on her. Would it be appropriate to give her an OTC cough suppressant or ask the doctor for something a little stronger?