What can you do if you think the Personal Rep is using the wrong death date for determining basis for Real Estate? The mother survived the father and had a life estate.

The father solely owned the property. The term 'remainderman' was not mentioned in the will so the Personal Rep attempted to get the court to award the real estate to her and her brother (children of the father), but the will gave the residue of the estate to the mother who also had 3 children. The court decided to award 50% to the 2 children and 50% to the mother's estate. She has been gone for 2 years. There is $100,000+ of capital gains reported on a 1041 for the mother's estate. The house was sold 15 months after her death for $716,000, but she is estimating the basis at his death (Dec 2018). I don't have a clue how this can be filed and it makes no sense to pass this expense down to the beneficiaries of the mother. What can I do?