I solved this problem.
I had the same exact problem as you guys. I have Office 365 installed on the bootcamp/Windows 8 side of my Mac. I also have Parallels 8. When I try opening Excel, Word, or Powerpoint through Parallels, they would crash immediately. However, they would work perfectly fine in Bootcamp/Windows 8 natively.
It was really hard to find, but I was able to find the solution somewhere else online. So, I'm sharing it here to spread the word. 
So, here's what you do:
Close Parallels, restart your Mac, and go into Bootcamp/Windows natively.
Now, open your Office 365/Office 2013 applications that would crash in Parallels. For me, I only use Powerpoint, Word, and Excel, so those are the ones I'll show you:
In Word:
Open Word.
Open a new document.
Click on the File tab.
Click on Options on the left.
Click on Advanced on the left.
Scroll down to "Disable hardware graphics acceleration"
Make sure it's checked.
Press OK.
Close Word.
In Powerpoint:
Open Powerpoint.
Open a new document (or "Blank presentation" as it's called in Powerpoint).
Click on the File tab.
Click on Options on the left.
Click on Advanced on the left.
Scroll down to "Disable Slide Show hardware graphics acceleration"
Make sure it's checked.
Press OK.
Close Powerpoint
In Excel:
Open Excel.
Open a new document (or "Blank workbook" as it's called in Excel).
Click on the File tab.
Click on Options on the left.
Click on Advanced on the left.
Scroll down to "Disable hardware graphics acceleration"
Make sure it's checked.
Press OK.
Close Excel.
Now, you can reboot your computer, go into Mac OSX, and open Windows through Parallels. Try opening those Office applications that would fail earlier. They should work now.
Apparently, all we needed to do was disable this "hardware graphics" thing, because it's incompatible with either OSX or Parallels. I don't know, but it worked. If you decide you need this hardware graphics thing enabled, you can always go back into Windows natively, open these Office applications, and uncheck those boxes, and just use Office in Windows natively.
Last edited: Oct 11, 2013