An autopsy is usually the best way to find out the exact cause of death. Even with an autopsy, it can be very hard to link death with the recent operation. Older adults getting a joint replacement for severe arthritis often have many other health problems.
Diabetes, heart disease, and lung problems are just a few of the more common conditions. Sometimes the patient has two or three (or more) problems all at the same time. These can increase the risk of complications after total hip replacement.
Two other important factors are (1) type of surgery done and (2) mental status of the patient. The seriousness of any post-operative problems that come up must be examined. Wound infection and blood clot are two of the more life-threatening complications that
can lead to death.
A careful review of your father's medical record may help you find what you're looking for. State and federal laws guarantee access to your own medical records in most cases. The executor of your father's estate can request your father's records. Depending on the state you live in, you may need legal help to get these records and/or the autopsy report.