It would require open-heart surgery to replace the valve, and if your father also needed
coronary artery intervention, then the surgeon would do a
coronary artery bypass at the same time.
Since the doctor gave you "options," maybe a calcified aortic valve is not the problem, but you can look up some pictures of the aortic root on the internet and see that the aortic valve is right there. Sometimes it does get calcified and stenotic, especially in older people.