Hi Shelly, I didn't find where Nicholas and Almira died, but here's what I did find.
In 1900, the Hilgerts were in Wd 2, Kearney, Buffalo County.Nicholas was b. Feb 1848 in Belgium, worked as a miller. Almira b Nov 1854, in Indiana; dau Mary b Dec 1886; son Ignatius b Feb 1891; son Sylvester b Aug 1892; and Cecilia b June 1894.All these children were born in Missouri
In 1910, in Shelton, Buffalo County, he was 61, and she was 55, and daughter Cecilia, age 13, born in Iowa, was with them.Nicholas emigrated in 1868.He was born in Germany, and his parents were Flemish, from Belgium.They were married 36 years in 1910, and she had born 9 children, all of whom were living.
I found Nicholas and Elmira Hilgert in the 1920 census, in Antelope, Kimball County, Nebr.They were 71 and 65 years old, and he was a miller at a flour mill.Cecilia, born Iowa, was living in North Platte Wd 3, Lincoln Co., Nebr., working as a telephone operator.
In the World War I draft registrations in Sept. 1918, I found Claude B. Hilgert, b 10 Dec 1883, cigar maker in Kimball, Nebr.He listed his nearest relative as Nicholas Hilgert.
Also in the WWI draft registrations in Kimball County were: Ferdinand Joseph Hilgert, b 29 May 1876, cigar maker, nearest relative, Mrs. Cecilia Hilgert, mother. (That's surely an error) Registered Sept. 1918. AND Ignatius Joseph Hilgert, b 4 Feb 1891 in Maryville, Missouri, unemployed rancher, married, had been a bugler in the US Navy for 2 years.Registered June 1917.
In 1920 there's a Claude B Hilgert living in Ogden, Utah;a Sylvester Hilgert in Brush, Colorado; and a Joseph Hilgert in Willow Fork, Moniteau, Missouri.
Anyway, I think Kimball county is probably the place to search for death/burial records for Nicholas and Almira.