Hi Maria, here's Hildur's North Carolina death record, it was listed under her married name, Sikora.
Hildur Holmberg Peterson, North Carolina, Deaths, 1931-1994
Name: Hildur Holmberg Peterson
Titles and Terms:
Event Type: Death
Event Date: 08 Dec 1965
Event Place: High Point, Guilford, North Carolina
Birth Year: 1881
Birth Year (Estimated):
Burial Date: 10 Dec 1965
Burial Place: Greensboro, N.C.
Cemetery: Forest Lawn Cemetery
Residence Place: High Point, Guilford, N.C.
Address: 711 Northridge
Gender: Female
Age: 84
Marital Status: Widowed
Race (Original): White
Occupation: Housewife
Birth Date: 26 Aug 1881
Birthplace: Ludvika, Sweden
Spouse's Name: Joseph Sikora
Spouse's Titles and Terms:
Additional Relatives: X
Informant's Name:
Reference ID: v 39B cn 39566
GS Film number: 1953694
And this is probably her in the 1930 US census, I could not find Hildur or Joseph in the 1940 census.
1930 United States Federal Census about Hilda Sikora
Name: Hilda Sikora
Gender: Female
Birth Year: abt 1881
Birthplace: Sweden
Race: White
Home in 1930: Chicago, Cook, Illinois
Map of Home: View Map
Marital Status: Married
Immigration Year: 1902
Relation to Head of House: Wife
Spouse's Name: Joseph Sikora
Father's Birthplace: Sweden
Mother's Birthplace: Sweden
Household Members:
Name Age
Joseph Sikora 45 (Czechoslovakia)
Hilda Sikora 49