Lil Meech Hangs With Floyd Mayweather & Rick Ross Amid 50 Cent Beef

50 Cent has been backing down both Big and Lil Meech on Instagram for days now ... but we're hearing his ex-'BMF' leading man can't be folded that easily!!! TMZ Hip Hop obtained photos of Lil Meech kicking it with some well-known 50 Cent opps…