when i using P3 to scan my site I got several errors on my site

1) My multisite is hosted on my dedicated server and my server only host this site.
2) I've increased my site memory up to 2GB
3) I've 35 plug- in installed on my site
4) I've been tried to deactivated all my plug in and re-activated it one by one, wont work.
5) When I'm editing on my back end sometimes i got "An error occurred while establishing a database connection" and i refresh it again it will going be fine.
6) I have installed Heartbeat Control, WP Rocket,WP Super Cache - Clear all cache,WP-Memory-Usage,WP-Optimize plug-in to speed up my site.
7) Im using P3 (Plugin Performance Profiler) to scan and i got this several errors

I got this errors:
Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 72 bytes) in /home/twmalac/public_html/xxxxxxx.com/wp-content/plugins/ultimate-branding/ultimate-branding-files/modules/site-wide-text-change.php on line 450

Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 72 bytes) in /home/twmalac/public_html/xxxxxxx.com/wp-content/plugins/ultimate-branding/ultimate-branding-files/modules/site-wide-text-change.php on line 518

Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 79 bytes) in /home/twmalac/public_html/xxxxxxx.com/wp-content/plugins/p3-profiler/classes/class.p3-profiler.php on line 300

Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 72 bytes) in /home/twmalac/public_html/xxxxxxx.com/wp-content/plugins/ultimate-branding/ultimate-branding-files/modules/site-wide-text-change.php on line 514

Can you help me ?

Cheers !

Cole