Frequent urination urge. Needed.

My father aged 90 is having problem in passing urine since last few months. He undergone prostate operation almost 11 yrs back. Recently since 1-2 mnths he experiences frequent urge for urination specially in day time (8-9 times) even without passing of urine on many occasions. As advised by doctor, the ultrasound suggest "bilateral mildly exogenous kidneys with renal cysts with significant PVRU". PSA tests conducted thereof revealed normal values. Electrolytes are also within normal range. Creatinine is 1.90 ( since prostrate operation the value is constantly within range of 1.75 to 1.90) eGFR 34 Serum urea. 46 Hb-A1c value 6.8 Tablet mirabegron 25 (SOS) and prostagard have been suggested but frequency of urge to urinate is still 8-10 times a day and quite a few occasions there is no / very less urination Do we need to go for some more investigations or these medicines are appropriate for continuation. Yr valuable suggestions & advices are earnestly needed. Regards