As a cancer survivor myself, had I chosen a total holistic approach, I would not be typing this now. I do believe in healthy eating (that old saying "you are what you eat") holds a lot of truth.
I know there are many that believe Big Pharma wants to keep people sick and there may be some truth to it but this isn't a one size fits all issue. I do my best to eat a clean diet and I pray I will never have to deal with cancer again but I also know that IF that happens I will work closely with my Dr.s to find the best options.
I know people who also think the way your daughter does. I do not engage into debate with them as there is no point. They are very closed minded in their thinking.
I feel so very bad for you that your daughter is so deep into this mindset that she thinks you would actually have your grandchild vaccinated without her knowing.
There are parents like your daughter who's child has become ill and the parents withhold conventional care and end up losing custody of the child. Family members will reach out and get a guardian ad litem to intercede on behalf of the child.
I'm so sorry for what you are dealing with. It's just so very sad. I hope you can find some peace.