Can't help definitively, but I think I found a solid lead:
Millarworld Annual are/were yearly compilations of short stories written & drawn by industry newcomers. Basically Mark Millar's company (also called Millarworld, Netflix absorbed it a while ago) hosts a talent hunt, and the winners get to publish ~5 page stories using his creations, such as Chrononauts, Kick-Ass, etc.
Top Cow Productions, a subsidiary of Image Comics (both of whom Millar has extensively worked with) has a similar annual tradition for their properties, like Cyberforce, Aphrodite IX, etc.
Unfortunately I can't easily find any documentation on this particular Variant Cover, but Mark Millar's comics often have several alternate covers per issue, which they try to market as collector's items.
The solicit for this issue does too (bolding mine):
So here's where speculation comes in, but I assume they offered several (or all?) of the creators a small 150 print run of Variant Covers to sell at conventions/signings/etc.
Looks like there were at least three July 2016 events where Steve Beach & Cliff Bumgardner signed issues of this Annual:
millarworld 2016.jpg
(Click to zoom)
Whether these were indeed sold at that press tour, or how many were signed for that matter I can't say for sure. However, I think you've got both signatures on there, not just the artist's (the scribble looks like a "C B" - Cliff Bumgardner to me). So I think it's plausible this issue was signed at/for that press tour, since the creators
seem to live in different States - and they'd be in one place for that press tour.