Nobody has to accept appointment as an executor and provided your mother has not started dealing with any aspects of the estate (called intermeddling) she may decline to act, or technically renounce Probate by signing a document called a Renunciation. If she wants to remain an executor but not be involved she can grant a power of attorney so some trusted person can act on her behalf. Alternatively if you give notice to her that you are to do so, you may apply for Probate with power reserved to her - this gives her the option of becoming involved at a later stage if she wishes to do so.