Current death records in the US are maintained on the state/local level. There isn't anything very recent for New York death records available online, and there are limitations on who can obtain the recent death records.
These days, the vast majority of elderly people in the US would get some sort of Social Security benefit, so their death would need to be reported to Social Security. Recently, the Social Security Death Index (SSDI) became unavailable to the public for three years after the individual's death, as explained here -
https://www.legalgenealogist.com/2013/12/30/ssdi-access-now-limited/ So, if it was a fairly recent death, she may not show on the SSDI because of that change.
