Yes, Yadkin County, NC was formed from Surry County in early 1850. It was listed as "Surry South Division" on the 1850 Census.

This morning, I found the reference to George C. Brandon in the Hutchins book house in the Yadkin County Public Library. Eli is also listed on the same page (p. 58). I have attached a scan of the title page and of p. 58. You may have already seen this, but if not, I hope it helps.
Terré