My grandfather was a Texas Ranger in 1860, he was ordered to retrieve only white people from Mexico. Grandfather Salinas was given the back end of Fort Ringgold. Because he intregrity the Calvary honored him with the back end of Fort Ringgold. Grandfather deed in witness to the fact that he owns the backend of Fort Ringgold. My mother was receiving funds prior to her passing away.
Welcome to the forum. Condolences on the passing of your mother.
If your mother was receiving royalties, then you need to contact the operator and notify them of her passing. Her estate will have to be settled so that the heirs can continue to get royalties if they are due. You might also check the unclaimed funds in the states where she lived. They cannot be claimed without title documents, but you will know they exist.