Sounds like you want the following

/(?:sudden|unexpected)? death(?! benefits)|deceased|passedaway|died|dy
+ing/
[download]

If you want to force the file to not have death benefits at all, then you could use the following:

/^(?!.*death benefits).*(?:(?:sudden|unexpected)? death(?! benefits)|d
+eceased|passedaway|died|dying)/
[download]

But probably be cleaner to just separate the regex's

!/death benefits/ && /(?:sudden|unexpected)? death(?! benefits)|deceas
+ed|passedaway|died|dying/
[download]