As previously written on the matter of what a "not-too-exotic" organic shipborne defense system against one way attack drones and USVs may be, I again posit that a navalized version of the gun/mini-missile setup would fit the bill quite well.
Autocannon with fuzed AHEAD shells and guided mini-missiles, with onboard FCR+EO set, integrated and cued with the ship's own onboard sensors and combat management system.
Two sets, one each side amidships, complementing the rest of a ship's main DP gun, CIWS sets and manually trained HMGs.
Until something more exotic comes along this is probably as straight forward as it gets while offering optimal capability with minimal risk.