Well, joking aside, in England at least, a pie of minced meat (usually lamb or beef I think) would be called Shepherd's Pie, or Cottage Pie, and the topping would be mashed potato, or occasionally pastry. With those two traditional names, we avoid terms like "minced meat pie" which would be easily confused with a "mince pie" which is much smaller, always with pastry, and is all about fruit and sugar.
How these two very different foods are described and distinguished in North America I don't know. Perhaps you need to sit down and have a long serious chat with your Grandma
