Please accept my condolences on your loss. If your mother had no will, then your step-father can not be an Executor. He may have been appointed as Administrator of your Mother's Estate. You really need to sit down with an estate attorney with litigation experience to discuss your options and to protect your interests. When someone dies in Pennsylvania without a Will, the surviving spouse is NOT automatically entitled to the entire estate.
NOTE: Mr. Fischer is an attorney licensed to practice in Pennsylvania. He can be reached at 610-269-0900 Ext 2 or firstname.lastname@example.org. This answer was prepared for educational purposes only. By using this site you understand and agree that there is no attorney client relationship or confidentiality between you and the attorney responding. This site should not be used as a substitute for competent legal advice from a licensed attorney that practices in the subject area in your jurisdiction and with whom you have an attorney client relationship. Frequently the question does not include significant and important facts and time lines that if known could significantly change the response. The law changes frequently and varies from jurisdiction to jurisdiction. The information and materials provided are general in nature, and may not apply to a specific factual or legal circumstance described in the question or omitted from the question.