This person is commemorated on a memorial in Nijkerk. More information on this memorial can be found (in Dutch) on the website of the Nationaal Comité 4 en 5 mei.
Petronella Nihorn was volgens het Gelders Archief archiefnr 0207 regnr 9104 op 27-08-1919 in Nijkerk getrouwd met Samuel de Liver. Zij hadden samen twee kinderen Sophia en Margaretha.
These persons are listed as residing at the same address. The source does not provide information about how they were related to one another.
In addition, a Jokos file (number 9031) on this household is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.