I located obituaries for both, but unfortunately, only Mary's obituary mentioned burial. I will transcribe both here to help anyone searching for the same families later.
Since Mary was buried at Washington County Memorial Park (in West Bend), it's possible that Anne was buried there as well, although it's odd that there was no mention. I checked the Washington County Historical Society's website and it says they "will email free death and burial index searches for one name per request for free. It is sent as an Excel attachment." I would recommend reaching out to them and seeing if they can check their database.
"Mary C McGrath of 917 S 7th Ave, West Bend, passed away at St Joseph's Community Hospital on Monday, Aug 23, at the age of 75. She was born at North Mankato, Minn, July 12, 1901. She obtained her Masters Degree in Education at the University of Minnesota after which she continued teaching English at Roosevelt High School in Minneapolis until her retirement in 1964 when she came to West Bend where she made her home with her nephew, Larry Kelly. Survivors include one brother, H.P. (Helen) McGrath of Kankakee, Ill.; one brother-in-law, John D. Kelly of Crookston, Minn., and nieces, nephews, other relatives and friends.She was a member of the National Retired Teachers Assoc, the AARP, the Minneapolis Federation of Teachers, Local 59 and a life member of the Retired Teachers Assoc. of Minnesota. Funeral services will be Thursday at 9:30 a.m. at the Schmidt Funeral Home with a concelebrated funderal high mass at 10 a.m. at St Frances Cabrini Church. Fr. Timothy Kelly O.S.B. will be the principal celebrant. Interment will be at Washington Co. Memorial Park. Visitation at the funeral home will be after 6 p.m. Wednesday with a prayer vigil at 8 p.m. Wednesday."
"Ann E. Kelly, nee McGrath, 917 S. 7th Ave., West Bend, died March 13 at St. Joseph's Community Hospital. She was born Sept. 28, 1898 in Mankato, Minn., where she lived until her marriage to John D. Kelly, on June 7, 1920. After their marriage they settled in Minneapolis. They lived there until 1931 at which time they moved to Whitefish Bay until 1942 and then moved back to Minnesota until 1962. Since that time they have been residents of West Bend. She is survived by her husband, three sons, Donald J., Alexandria, Minn., Larry W., West Bend, Fr. Timothy Kelly O.S.B., Mt. St. Benedict, Crookston, Minn., and one daughter, Sr. James Thomas O.P. of Chicago. Two sons preceded her in death. She is further survived by 17 grandchildren, one great-grandchild, three daughters-in-law, one sister, Mary C. McGrath, West Bend, and one brother, Harold P. McGrath, Kankakee, Ill. Funeral services will be Saturday, March 16, at 9 a.m. at the Schmidt Funeral Home followed by a con-celebrated funeral High Mass at 7:30 a.m. at St. Frances Cabrini Church, with Fr. Timothy Kelly principal celebrant and Fr. Rock J. Janowski co-celebrant. Visitation at the Schmidt Funeral Home after 4 p.m., Friday, with parish vigil at 8:15 p.m. Friday."