The PCV valve is designed to allow vapors (pressure/vacuum) to be removed from the crankcase, it then passes to the air cleaner where its passed thru another filter and some is drawn back into the carb for another pass thru the cylinders.
The way you have that breather routed and hooked up to the carb vaccum, its basically acting like a straw in a soda can sucking the oil out, routing it to the air cleaner will reduce a substantial amount of vaccum and oil being drawn up/out, the PCV valve has a "stopper" in it coupled with the smaller orifice and less vaccum will reduce/eliminate that oil drip.
Now,
Depending on where you live (emissions), you could simply route that breather hose to the air cleaner and that would probably stop the oil drip as well, or just run an open breather with no nipple or hose and again, chances are good your oil drip will stop as well.