The product label does not state a specific amount of water to use to water in after the application however typically as long as you do not overwater to the point of puddling or run off, the granules would disolve into the soil.
Per the product label of Bonide Ant, Flea & Tick Killer Granules, “Apply with a fertilizer spreader when the grass is dry. Water lawn lightly after application and repeat as necessary”
No, overnight or morning dew would not be sufficient moisture/water to activate the Bonide Ant, Flea & Tick Killer Granules. After the application, water the area with ¼ to ½ inch of water to effectively activate the granules.
Please view the full product label for more information.