In the 1891 census , I located Peter Holland living on Tucka Tucka Station, in the county of Stapylton NSW. Whoever transcribed the Census for online viewing recorded the location as Jucka Jucka.; Yetman Station was also recorded on the same page and it seems these two stations are part of Yetman. All these stations belong to the Gwydir LGA. Warialda is a town in the Northwest Slopes region of New South Wales, Australia, in Gwydir Shire. Situated on the banks of Warialda Creek, the town's name means "Place of Wild Honey.
In this census Peter has 2 males and 2 Females residing there. Next line shows a James Hildrew residing with 1 male and 3 females listed. This would be worthwhile pursuing James' death in 1916 at Warialda gives his parents names as John and Rose. (possibly Elizabeth's brother).
Meanwhile little can be found in this quick search on Peter ,the 1913 census has Elizabeth, Peter and Peter John, living at Boggabilla, Gwydir.
There are two Peter John Holland's dying in Queensland, the first in March and the other in May 1948. and looking at the census, it seems these could be from the Walrialda area .Closer scrutiny shows that Peter John Holland who died 8 May 1948 in Queensland has mother Elizabeth Hildren and father Peter (QLD BDM 1948/B016472).
Now I also found another Elizabeth Hildrew who married a Donald McPherson in 1920 and she came from Queensland, she possibly is a niece to your Elizabeth. Her obituary can be found at OBITUARY (1929, November 26). Glen Innes Examiner (NSW : 1908 - 1954), p. 4. Retrieved May 3, 2017, from http://nla.gov.au/nla.news-article180834940
Hope this is helpful