Table: Event
==============
ID
OldUserID
NewUserID
Date


Table: User
==============
ID
Forename
Lastname
....

SELECT U.Lastname,U.Forename,IFNULL(U1.cnt,0) CountOldUserID,IFNULL(U2.cnt,0) CountNewUserID
FROM User U, Event E
LEFT JOIN (SELECT OldUserID id,COUNT(1) cnt FROM Event GROUP BY OldUserID) U1 USING (id)
LEFT JOIN (SELECT NewUserID id,COUNT(1) cnt FROM Event GROUP BY NewUserID) U2 USING (id)
WHERE Month(E.date) = Month(Now()) AND Year(E.date) = Year(Now())