Best wishes, you seem to be in a challenging situation. You can express your intentions to have your kidney directed to your mother after your death to your loved ones, as it will be up to them in that eventuality. They may be guided by written documents, or may not. Also, the full array of medical testing and judgement as to the appropriateness of the match may suggest it is not in her best interest. Finally, she must consent, and a child predeceasing a parent is always a tragic circumstance. If your wishes are a surprise to her at that time, that would be very stressful. Again, best wishes.