index.php Line 4 - Undefined Function

My team and I were recently experimenting with different Omeka themes, however, when we tired to revert back to our original theme (Seasons) that we've had for some months, this statement appeared on the homepage:

"Fatal error: Call to undefined function option() in /home/pgabrielle/ on line 4"

We assume this message is somehow a result of the fact we have an older version of Omeka when a new version is available.

How can we get our site back up and running until we are ready to make this version update?

Yes, it looks like a version mismatch. option() was introduced in Omeka 2.0, so I'm guessing that you are using Omeka 1.x, but have the version of seasons for Omeka 2.x.

Downloading the Seasons theme that matches the version of Omeka you have should get things back to normal.