Mid 2011 iMac *** Panic Report ***
any idea why my wife's iMac is getting this attached panic report?
It appears to be a hardware fault.
If you have any external peripherals attached, you can try running with them unattached to see if it still panics.
You will likely need to take it into an Apple Store or certified repair center to have it evaluated.
Things you can do that might possibly fix the problem:
Erase and reinstall. The restore from backup.
Neither of these will likely fix it, but they might in very rare circumstances.