"Jive" of Sub Brief gives a briefing on Soviet ASW Helicopter Tactics in the Youtube here https://youtu.be/eBxXIwJCjv4 and above.
The helicopters illustrated are Kamov Ka-25 Hormones especially designed for ASW. They carry a dipping sonar and a light weight torpedo or 2).
Helicopters work more effectivey in concert with warships. The warship and its helicopter can operate active and/or passive sonars. For example (a Harbin Z-9) can operate from a Chinese Type 056 corvette of around 1,500 tons.
A rotary wing UAV eg. the VSR700, of 700kg max takeoff weight, might be able to operate off an even smaller vessel,