The Backline 112 has a output jack on the back of it (the speaker is not hardwired to the amp), so you could use the amp to drive a different cabinet if you wanted. It's only 100W though, and as bass amps go, that's not a lot. You could certainly try it.
Does the club have a sound guy or will your band be running the mix yourselves (how small of a club are we talking)? You could mic the 112 so that it will go through FOH, that would make up for any issues you might have cutting through the mix with a 100W amp.
Even small clubs can be plenty loud, so I would mic it. When I used to run sound at a church my wife and I attended, one of the guitarists had a little 15W practice amp that we miced and ran that line signal through FOH.
After the gig you'll have a better idea of what you're going to need power wise.
Ric5: "We dare not play chords for fear of knocking the planets out of alignment." Yamaha BB Club #66