"That is hers."
Quick question: Does もの basically mean "thing"? I've noticed it in a few other words like 食べもの and のみもの which mean "food" and "drink" respectively, right? This leads me to think もの pretty much means "thing" like "thing to eat" or "thing to drink." Or am I completely up the wrong tree?
Depending on the context, それ may also be accepted. This would make sense in a situation where the other speaker is asking whether something they're holding belongs to anyone (although in this case, それ would be implied and wouldn't be required anyway).