Is there a webpage where they list the estimated number of students who apply to the specific Level II programs at McMaster? I remember in high school getting information that included how many spots were available vs. how many people applied to a program, but I have no idea where to find that now.

I'm specifically interested in knowing the stats for the PNB program and all its branches (especially the Mental Health Specialization).

Any help would be greatly appreciated

I don't know if they still have these but when I was in first year, my faculty office had a list of the average CA and average number of people enrolled for the different level 2 programs. This was the science faculty so I don't know if it's the same for all faculties but it wouldn't hurt to go check at yours.
There was also a handy google doc posted on macinsiders but I can't find it now.
Still, the science or social sciences faculty would be a more reliable source for PNB info.