Losar-H is the brand name of a product that contains two medicines: losartan and hydrochlorothiazide. It is well known that losartan can cause dry cough and some patients need to stop the medication.
It is always advisable to use medicines individually and not as a combined pill since it is very difficult to determine side effects.
There has been lot of research in advanced countries like US and Britain as to the best way to treat high blood pressure. As per internationally accepted, standardised evidence-based guidelines, in patients aged 55 and over, first choice of initial therapy (in a case like your wife) should be either amlodipine (sold as Amlodac) 5mg once daily in the morning or a diuretic such as metolazone (sold as Metoz) 2.5mg in the morning. If two drugs are required then Amlodac and Metoz, both can be given concurrently.