LinkedIn keeps suggesting me my mother who passed away 4 years ago. Every week, without fail, I get an email telling me that I should totally connect with her. It’s highly annoying and no matter what I do to my email preferences, I keep getting the same damn email.

Agreed. A couple of times a year i go try and purge the stuff they send. I do want to see the job searches that I've asked for, i don't expect to see any job posting I've even glimpse at, or anything vaguely associated with it. In all seriousness someone at Linkedin is getting paid per email sent.