The way I see it is that both Gmail wants her as a customer to click on ads, and she wants to use the Gmail service, because she likes most features. In that view pushing her to stop using the service is a loss for both, I can not see that being the best solution.

In my opinion saying "Happy fathers day" or having a Google Doodle is one thing. Putting it like a reminder in a personal setting, when you for example don't want to speak with your abusive father, is another.