I found the burials of James Lynch and Anna (unk) on findagrave. Maybe the cemetery could point you to a death record or try the Town Clerk in Turtle Lake, McClean, ND. Her dod is not legible, but after 1925 from the census data,
: Turtle Lake Cemetery, Turtle Lake, McClean, North Dakota
: Father: James Lynch
: April 3, 1852 - Jan. 13, 1926
: Mother: Anna xxxx? 1851- xxxxx<ref>Find A Grave Memorial# 52276110
https://s3-us-west-2.amazonaws.com/find-a-grave-prod/photos/2010/175/52276110_127750414873.</ref>
North Dakota Census, 1925 Turtle Lake, McLean, North Dakota
: James Lynch M 74
: Anne Lynch F 74
: Martha Lynch F 30 <ref>"North Dakota Census, 1925," database with images, FamilySearch (
https://familysearch.org/ark:/61903/1:1:QVR9-MBPJ : 30 June 2016), James Lynch in household of P O Bergo, Turtle Lake, McLean, North Dakota, United States; citing sheet number 3, family number 1, State Historical Society of North Dakota; FHL microfilm 1,731,400.
https://familysearch.org/ark:/61903/3:1:3QS7-L9LK-D8FP?i=385&cc=2351024</ref>