Sources for "ping" bundled with Mojave 10.14.6? I am interested in knowing whether the "ping" utility shipped with Mojave 10.14.6 sources are open.

man ping ends with BSD March 29, 2013 BSD, but it seems that FreeBSD's version of ping is not the same as the one I use locally:
https://github.com/freebsd/freebsd/blob/master/sbin/ping/ping.c
Apple puts all opensource content on https://opensource.apple.com.

I didn't find the 10.14.6-related sources there but ping version included in 10.14.5 is available here. At first glance Apple seems to have added some stuff, but you may need to run a diff to see all the changes.