Hello, Thys. According to the 1930 US Federal Census, there was an Edward De Jonge born about May/June 1929 in Michigan to Wilhelmina H. De Jonge, who was widowed by April 1930 and living in Holland, Ottawa County, Michigan. Her children were:
Charles, b. abt 1909; employed at furniture factory Rena, b. abt 1912 Arthur, b. abt 1919 Herman, b. abt 1922 Harold, b. abt 1924 August, b. abt 1925 Grace H., b. abt 1926 Edward, b. 1929
The first three children were born in NL and emigrated in 1920 with parents. The rest were all born in Michigan. Perhaps you can find Wilhelmina buried in the same cemetery along with her husband.