Fatal Error: Allowed memory size exhausted

I am trying to save changes to one of my events on my WordPress site, but am getting this fatal error:

“Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 55513375 bytes) in /home1/lsyelich/public_html/beta/wp-includes/wp-db.php on line 1094”

What can I do to resolve this issue to save my content?

Thank you!