The traditional limit was 22 nautical miles, which did NOT include Baltimore's Inner Harbor or parts of Washington, DC. For the Class of 2012's PPW, the limit was extended to 25 miles. For the Class of 2013, every Plebe was matched with a sponsor family. Since a number of sponsor parents live between 25-30 miles from USNA, the limit was extended to 30 miles.
As others have said, things change every year, so what was acceptable last year may not be this year, and you probably won't know that until after I-day.
Having close contact with Mids from 2011, 2012, and 2013, let me emphasize the points that USNA1985 made. Even if today your Plebe-to-be says that it will be fine to see friend X or relative Y, he/she may not feel the same way when PPW actually arrives. Try not to make any plans whatsoever for PPW other than to meet the needs of your Plebe.