N.B. - Trending searches are not the same as search suggestions. Search suggestions happen when you type in a term like "dance" and it finds various dance-related terms to search on. Trending searches is what everyone else is searching on at this moment - usually things in the news headlines, celebrity stuff and other uselessness.
I don't have this problem on Chrome, only on Firefox. In another thread someone suggested running AdBlock Plus, but I'm running that, turned up to the max, and it makes no difference. OS is Windows 10. Latest version of Firefox.
EDIT: added image
21 Answer
You appear to be talking about these.There aren't a feature of Firefox; They're a feature of Google.com.
The solution is simple. If you want to use Google in Firefox without seeing the Trending searches, then use it from either the top bar on any page that you've got open or use the handy search bar that's on Firefox's default homepage.