How to find files that have certain string in last line

Let’s say you have few files

string
|-- 1
|-- 2
|-- 3
|-- 4
|-- 5
|-- 6
|-- 7
|-- 8
`-- 9

And they may end with two different endings: aaa or bbb.

Finding list off files that have given string at the end can be done following way

> find string -name "*" -exec tail -v -n1 {} \; | grep "bbb" -B1

on macOS you have to go slightly different way

> find string -name "*" | xargs tail -1 | grep "bbb" -B1