Translation:The bear is growling, because there are a couple of wolves nearby.
DL is being a bit incoherent because if really going into details: nearby = lähistöllä, lähettyvillä; near = lähellä. And I don't know if DL has ever introduced the word "lähistöllä"? (As a native Finn I haven't been going through the course but probably should because of things like these.) So if it really is using only 'lähellä', it should definitely accept near and nearby as correct answers on every sentence, unless English for some reason can only use one. The difference between these Finnish words is anyway very small.
They're not interchangeable in English. Here 'nearby' is correct and 'near' would be wrong. English and Finnish have very different grammar so translations have to follow the meaning not the words.
e.g. When the wolves are near the bear, the bear knows that there are wolves nearby (I hope those both translate to "lähellä" otherwise I haven't made my point haha)
So it must be the English grammar, then. In Finnish you can use "lähellä" in the place of them both so that's probably what is confusing the learners here - the English and not necessarily the Finnish. That's why I'd probably introduce a word "lähistöllä" as the translation for "nearby" because it has a slightly different meaning and would be much easier for the learner to choose between near and nearby if English is not their native language.
But giving learners the idea that lähistöllä = nearby and lähellä = near is not correct. As just demonstrated above.
This is a course primarily for english speakers so they need to get accross the idea that finnish isn't like our language and we will need to use lähellä in ways that are not exactly congruent to english. So I don't think avoiding any difficult english grammar is a good idea.. I do realise that the course isn't yet available for any other languages but until it is, we'll just help out the non-native english speakers in the comments.
Well, that's also true. If the exercises only had lähistöllä for nearby and lähellä for near, then it would rise even more questions, especially because every dictionary translates both to "lähellä". I couldn't even find "lähistöllä" from dictionaries (but I know that it's a word, because I'm from Finland and use that a lot), apparently it's from the word "lähistö" that I didn't even know would mean "neighbourhood". I have never really associated "lähistöllä" with neighbourhoods, even though that's pretty much what you'd mean because usually people are near buildings ad neighbourhoods :D