Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; <Control>(Mac:<Command>)<Shift> A)

In the Add-ons Manager, on the left, select Extensions. Remove ******* Anything. Now do the same in the computers Programs Folder.

Windows: Start > Control Panel > Uninstall Programs. Mac: Open the "Applications" folder. Linux: Check your user manual.

Bookmark and use this; Mozilla Search Reset {web link} This add-on is very simple: on installation, it backs up and then resets your search preferences and home page to their default values, and then uninstalls itself. This affects the search bar, URL bar searches, and the home page.

Settings Guard for Firefox {web link} Detects and resets changes to settings that are frequently done by add-ons and application installers.

Thanks for all the suggestions. I tried everything in the order you suggested and with the exception of Settings Guard, which has been removed by its author, I had no luck. Bing.vc still reigns supreme over my start page. I can't even find any reference to it in all of Firefox through a search of everything. I don't know what to try next but this thing can't be unremoveable can it? Would dropping back a version or two of Firefox be worth a try? I am using the Beta, version 39, currently.

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Are you using the built in Firefox about:home page?

I had a stroke and can't be as helpful as I could. I've called the big guys to help you. Good luck.

about:preferences#search<enter> in the address bar. If it is listed, remove it.

You may have ad / mal-ware. Further information can be found in the Troubleshoot Firefox issues caused by malware article.

No, I am not using the about:home Firefox start page. I am using Yahoo.com as my start page. I have tried the Preferences section and removed Bing from my search listing. It lists Yahoo as my home page and I have also run Malware bytes, Ccleaner, Spybot S and D, Super Spyware Blaster and others recommended online. I have also scanned with AVG. None of these have picked up anything suspicious. I am going to try an online scanner like Panda Cloud AV. Thanks again for your help.

 For some unknown reason, Bing.vc is gone.  Don't have a clue what I did but something worked.  Your help was greatly appreciated.