Kernel panic during sleep mode
Try booting the MacBook Pro into Recovery or Internet Recovery mode (hold down cmd-R when booting for Recovery mode, or option-cmd-R for Internet Recovery mode).

Now you have booted in a "known good" configuration of software which is unaffected by any changed you may have made to the normal operating system on the Mac.

If sleep mode works fine here without kernel panics - you'll know that you have a software related problem.