Parents are most likely Samuel Hollenbeck and Susannah Ruck.
"Michigan Death Certificates, 1921-1952," database, FamilySearch(https://familysearch.org/ark:/61903/1:1:KF7F-4TL : 12 December 2014), Austin Hollenbeck, 13 Feb 1934; citing Constantine, St Joseph, Michigan, United States, Division for Vital Records and Health Statistics, Lansing; FHL microfilm 1,973,109.
Image of the death certificate can be found here:
http://seekingmichigan.contentdm.oclc.org/cdm/singleitem/collection/p16317coll1/id/645177/rec/3