I am amazed that anyone in this day and age is trying to tell a daughter that she is not the mistress in her own home with the care of her own children. It is highly likely that this was discussed with her DH and he is in agreement.
At what point do you self-centred mothers give up dominance over your children's choices and decisions when they have set up their own homes with their own children? Just shaking my head in disbelief.
No one is saying "no visiting ever, period". PT's daughter is simply saying "These are my house rules - vaccines necessary for those in close contact with my children upon the advice of healthcare providers." She has every right to do so. Respect that right! You don't have to visit her or the children if you are so opposed to having the vaccines. That is your right!