How do I challenge the actions of the executrix of my father's estate?
You may file a petition with the Surrogate's Court demanding that the executrix file a judicial accounting. Once it is filed you may file objections and have the court address your grievances. However, you cannot file the petition unless at least 7 months have elapsed from the date the executrix was appointed by the court.
This is a very broad question. It would depend on the issues that you wish to challenge.
Mike.
Both responses are correct, as it depends upon the grievance, which, if appropriate, allows you to bring an action before the Surrogate's Court. More facts about the nature of the grievance are needed to provide a complete answer.