You could actually file an initial and final return (Form 1041) for the estate by choosing a fiscal year.
See https://www.irs.gov/instructions/i1041#en_US_2021_publink1000285987
For example, your fiscal year could begin on the date your father-in-law passed (November 25, 2021) and end on October 31, 2022. You would select this fiscal year on the first return the estate files.
