Call to undefined function siteorigin_page_setting() after site hack

It appears my site was hacked recently, and in trying to recover from it, I am getting this error. I downloaded a fresh copy of the Vantage theme (which I was using) and replaced the files. The error persists. I have my customizations in a custom plugin; I renamed the plugins directory (“disabled the plugins”) and the error is still there (figured it was worth a try). Please help.