The responsibility for parliamentarians lies with the Sergeant-at-Arms. There is work done, obviously, in collaboration with PPS and the RCMP, depending on the level of threat, but the Sergeant-at-Arms is the first person who is responsible.
Evidence of meeting #10 for Public Safety and National Security in the 44th Parliament, 1st Session. (The original version is on Parliament’s site, as are the minutes.) The winning word was enforcement.
A video is available from Parliament.