At 75 I just started whole hog, and had 'carb flu' for a week. That was OK for me, maybe not for her.
2 documentaries helped me along, King Corn, and I can't remember the other, but it had to do with modern farming. Wheat Belly is a good suggestion. King Corn points out that the corn grown today is poisonous to man and animal. It has to be soaked in sulfuric Oxide to break it down at the beginning of processing. SO2 is also poisonous and an immediate killer taken straight.
When she and I were young, we both ate butter. But when I started PB after I bought the butter and started to use it the first time, it wasn't as easy as I thought. I wondered if I really, really wanted to do this.
PB is a very easy read, but a little dull. give her a copy but don't press completion.
How is she with dairy. If she can, she'll love cream, butter and all the great things she eat when she was young.