Hello zmtgf,
the error message indicates WordPress has 134 MB memory to work with. You can try increasing that to 256 if you like. Instructions for how to do that can be found here.
Two other things you can do is
1. If set to less than 256, you can you can increase "How much memory should Wordfence request when scanning" setting. It's under "Other Options" on the Wordfence "Options" page.
2. You can choose to include fewer things in the scan and see if you can narrow down which option correlates to running out of memory. By doing that you could determine if there is a very large amount of data somewhere that Wordfence is trying to deal with. This setting can be found on Wordfence "Options" page under "Scans to include".