As per our policy, we don't delve into predicting death of people. Still since you have asked a question, will provide some clarity.
Starting February 2023 and untill 2 years from there could be difficult for your father health wise. Any unfortunate event can happen around February 2023, incase he passes that time then September 2023 can be a crucial time.
If he survives both these times and shows recovering status in year 2024, then he can come out of this situation and live longer.
Moon-Ketu in lagna and Saturn transit in lagna can be a crucial time if health is deteriorating. Such times can be accentuated when Rahu enters Maraka sthana in Sep 2023 for the native.
Saturn transit through first house will remain crucial for the longevity of the native, can also restore health.