does executor of a minor's property have right to sell without notification to custodial parent in NC

Yes.  In his Will, grandfather could give his property as he wished.  It sounds like he directed his executor, whose job it is to carry out the instructions of the Will, either put the property in a trust or is acting as trustee for the minor child's inheritance.  The executor has the ability to sell real estate unless the Will specifically says he should not sell it.   I recommend that you read the Will closely.  As your minor son's mother, you do not have the ability to influence how grandfather's Will is probated or how assets given to your son are administered if someone else is named in the Will to do so.  If the Will merely says that the property is to go to your son and has no provisions that give an executor the authority to hold a minor beneficiarie's assets in trust or to sell them, then you could ask the court to allow you to hold this land for your son until he is 18.  If you believe that the executor's selling the land is harmful to your son, you also could challenge this action in court.  But, if the Will authorizes it, you are unlikely to succeed.