I spoke with my dad this morning. He was lucid. He detailed everything that happened yesterday. And he's embarrassed to the core by it.
I told him that what he did showed how much he loves the members of his family and what he would do for us.
Both he and my mother put a stop to it as it was unfolding, but since they don't have caller ID, they have no way of tracing the calls. It turns out that not only did the first caller use my nephew's name, he also used the word "Opa," which is what the nephew uses to call him. So, whoever the scammer was did some homework.
It turns out that CVS will refund one of the money cards my dad bought, and the rest are good to be used wherever, so they aren't out any money. But, oh, is his pride hurt.