I've got a ceramic plaque with cats on it, being a "cat-astrophe" (boom-tish) that FIL's partner gave us. Yes, we like cats. No, we don't really want stuff with cats all over it. I get it out of the Useful Drawer when I know they're coming over, and put it up where I already have something hanging. Once they've gone, I take it down and put it away again.
I do think it's a mistake to give other people artworks, but if you do - in fact, give anybody anything - then don't, no matter what, ask them where it is or indeed anything about it. My mum does this, she made bedspreads for her GC and wants to know a) what did the child think of it b) how often does he use it c) how much another child loves hers, etc etc. I squirm as ds isn't bothered about it really, it features things he was into as a toddler but doesn't want over his room now he's older. I did thank her for her efforts but I wish it wasn't loaded with so much expectation!
At the end of the school year, I gave ds's TA a hibiscus plant I grew from a cutting (she'd said that she enjoyed gardening, who knows if it was true or not) but once it was in her keeping, I never once asked her how it was doing or referred to it in any way. To do otherwise is an imposition, just as much as giving somebody something they might not have been yearning for...
OP, your DH needs to step up and say "Thank you mum, but it's not in keeping with our style, I hope you can return it". If it was a small thing you could just put it away, but something that large is really impractical!