Your information is a bit sparse. O’Neill & Boyle are very common names around Randalstown so it’s hard to advise without a bit more information.
I can see that John O’Neill married Catherine Boyle c 1861 in Drummaul parish. What happened to them after that? Where did they die and are there any parents names from Catherine’s death certificate?
I can see a Hannah Boyle marriage to Bernard O’Neill in 1864 in Randalstown chapel. One of the witnesses was Bridget Boyle. Those names fit but I have no easy way of saying whether it’s your family. That family lived in Drumkeeran. Father was John Boyle, farmer. But it’s hard to say if there’s any connection with your Catherine without some more information.
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1864/11607/8272063.pdf
That John Boyle had plot 11 in Drumkeeran which was a 14 acre farm which he farmed jointly with Felix Boyle. Is Felix a family name?
Felix died in 1910 aged 102 which is quite impressive, though probably not correct:
https://civilrecords.irishgenealogy.ie/churchrecords/images/deaths_returns/deaths_1910/05414/4512817.pdf
His wife was Eliza and died in 1890:
https://civilrecords.irishgenealogy.ie/churchrecords/images/deaths_returns/deaths_1890/06099/4740498.pdf
Felix didn’t hang about and remarried Sarah McKay in 1891:
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1891/10672/5889149.pdf
Household in 1901:
http://www.census.nationalarchives.ie/pages/1901/Antrim/Shilvodan/Drumk…
There was a John, son of John (deceased) who married in 1865:
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_re…
John junior died in 1888:
https://civilrecords.irishgenealogy.ie/churchrecords/images/deaths_returns/deaths_1888/06179/4766358.pdf
This looks to be his widow in 1901:
http://www.census.nationalarchives.ie/pages/1901/Antrim/Shilvodan/Drumkeeran/916639/
That John was born c 1840 according to his marriage certificate and so could be Catherine’s brother. But I don’t have enough information to say for certain. It’s all rather speculative.