It's a pity that the 1900 and 1910 census records aren't indexed on Ancestry yet, as are 1920 and 1930, however knowing where you're trying to find the people you're looking for is almost as good as an index, when the clues are as strong as they are here. Therefore:
Census, 1900, Burke Co, NC, Lovelady, ED 10, p. 180a&b, household 171-173: Abernathy, William P. age 49 b. Nov 1850,Maggie, age 42, b. Sep 1857. Maggie had 9 children, of whom all were still alive at the time, albeit not all 'at home' with their parents. The household in 1900 included the 5 youngest children: Charles (17), daughter May (15), 'Bennie' (13) whom I believe is your Benjamin, son Everet (8) and son Bertie (4). William P. Abernathy, wife Margaret, and the 4 elder children were found on the 1880 Census for Burke Co, NC, p. 263a, in the Lovelady community. William is listed as a Carpenter. William is listed in the 1870 Burke County NC census as 'Willie P'. Census Roll M593_1126, Lovelady, p. 319, household #43-43, date 23 Jul, age 16. His parents are Logan Benjamin and Catharine (Jarrett) Abernathy.
Logan Benjamin Abernathy (1824-1909) was the next younger brother to Robert Laban Abernathy, Founder & President of Rutherford College, who also had a son named William, as you discovered, but my database shows William Ellis Abernathy married to a Miss Bertha Thomas Winn, and the 1900 census confirms that it was his cousin 'Willie P' who married Maggie. Estimated date of that marriage: 1871 or 1872. A letter to the relevant Burke County officers may well yield a certified copy of the license.
Robert Laban and Logan Benjamin are the two eldest children of Turner T. and Fannie (Whitener) Abernathy. I can trace that couple back thru the 1840, 1850, and 1860 census records but cannot identify two of the 10 children as yet. I cannot fully document at this time Turner's link to his presumed parents, Robert Abernathy and Sarah Nichols. Nor can I demonstrate with solid evidence that Robert's link with parents, either. I, personally, have Robert tentatively shown in my database as a son of David and Ann (Turner) Abernathy, but the evidence is not as conclusive as I would like. And there are those who claim Robert as a child of a different set of parents, pointing to some of the same documentation to do so. That far back, things can sometimes get murky, you see?