I found reference to an organization called Netherland Israelitisch Sick Fund. Given that one of the ancestors had been born in Holland, maybe they were members.
Hope this helps a little.
Glenda [Rubin] SF Bay Area
On Wed, Apr 3, 2019 at 6:09 PM Madeleine Isenberg madeleine.isenberg@... wrote:
I found this acronym, N.I.S.F., inscribed above the Peh"Nun on stones of a husband and wife, buried in the USA. I cannot find a meaningful expansion, although I'm assuming it must be a sort of "Rest in Peace." The husband was Sephardic, and had been born in Holland; his wife in England.