Hi
Enlarged prostate seen on ultrasound itself is not an indication for treatment. If your father has some difficulty in passing urine then it needs further evaluation
Next Steps
I would advise your father to get a blood test called PSA done, He will also need a test called uroflowmetry and post void residual uine assessment. If these show that there is significant obstruction to urinary flow then it needs treatment either in the form of tablets or surgery depending on the severity of obstruction.