If your grandmother died at the asylum, she may be buried in the Chippewa County Poor Farm Cemetery. The cemetery is in Chippewa Falls between the old Asylum building (abandoned, as far as I know) and St. Joseph's Hospital.
I copied my great-grandfather's asylum records at the Chippewa County Historical Society. Volunteers there were also able to look up where he was buried, including the specific location in the cemetery. He died at the asylum in 1917 and is buried in the poor farm cemetery. Cemetery markers are small and flat and some (like my great-grandfather's) have sunk and are hard to find.
Check out the historical society's website at:
If you're not in the area, I believe you can ask them to do some research for you for a fee.