Do I have any claim to my brother’s estate if he had no will, spouse, or children?

No. Since your father is alive, your father (and your mother) would be the heirs for your deceased brother. Being a guardian/conservator does not give people rights of inheritance. A guardian is appointed to care for the person if someone cannot manage his/her personal needs. A conservator manages the money or property for the incapacitated person. When the incapacitated person dies, then the person's property is distributed by the terms of their will. if any, or the state intestacy laws of the state where the incapacitated person lived prior to death. Usually, if the person had no spouse, children or lineal descendants (grandchildren, great grandchildren) then their property goes to their parents, if living. Only if both parents are dead would the siblings inherit. The duties of the conservator would be to turn over any assets to the personal representative of the incapacitated person's probate estate. In this case, your father would probably be the best person to assume that role and he would just change hats. You mention SC - I am not licensed to practice in SC. I am licensed in NC. Your father, since he is conservator, really needs to speak with a probate attorney to find out his responsibilities.