Capital gains liability & filing by Estate

Father died in 2020, Mother died in 2023. Dad's stock was never transferred to mothers name. As executor of Mom's estate I transferred ownership of the stock to mothers estate and liquidated it along with any real estate and other assets.

I filed mothers final returns in April 2024 but stock did not sell until 2025. From date of death to sale of stock it gained about $25,000 in value while held by the estate. The estate was well below any federal limits requiring estate tax. My question is do I need to file another final return to reflect the capital gains of the stock?

Secondary question is that all proceeds are being evenly divided between my siblings and me, are K-1 forms required?