I would say the easiest way to make money would be receiving government benefits, they require very little even no effort and are stable guaranteed income.
The second easiest way is probably a really simple mindless job like working in a quiet shop or local supermarket, again guranteed £700 - $900 dollars pcm and little effort but this one does require a lot more time.
I am not trolling by the way, I know it might look like that but you wanted easiest and I would seriously consider the above 2 methods if easy is your goal.
There are IM ways to make money but even the simple ones of them are not as easy as the above, maybe some basic IG or writer or VA stuff but they wont generate as much as the above 2 methods and are never guaranteed.
IM can be simple but it is not easy, the effort, time and dedication required is way more than just working in McDonalds.