If you are using a sensor for the date, the conditional card is what you probably want to use. So, if you have sensor.my_event and it occurs today, it’s value would be on and you can use that as a state condition.
Then as Bill suggests, use a conditional card checking the state of sensor.date. Note that the date sensor uses the correct date format rather than MM-DD-YYYY, so for Card A, check for '2024-05-01'.