I think it sounds like "The wolf is not eating her." In English we emphasize the word with tone, but in other languages putting "not" or in this case "ikke" in front of her or "henne" emphasizes "not her". So, perhaps we should ask if we can put "Ulven ikke spiser henne." Of course then, the wolf is not eating her, but he might be doing something else to her. I guess it negates the whole sentence if "ikke" is at the end of the sentence?
This is basically correct, except for the "Ulven ikke spiser henne" example, which is ungrammatical. The verb has to be the second constituent of the sentence, as Norwegian is a V2 language (look it up, tl;dw).
But the meaning also depends, like in English, on intonation. The sentence "Ulven spiser ikke henne" could both be understood as "The wolf is not eating her.", "The wolf is not eating her." and "The wolf is not eating her.", and even "The wolf is not eating her". It all depends on the level of stress you put on the words.
You are correct in assuming that putting "ikke" at the end negates the whole sentence.
Based on discussions of "ikke" placement here, I tried the following on a whim: when asked (in the "definites" section) to write "They are not eating the meal", I decided to answer with "De spiser måltidet ikke". But Duolingo told me that was wrong, and that the correct answer is "De spiser ikke måltidet" (which is what I would have said before reading comments here). So, was my response really wrong, or is Duolingo wrong, or is there still something missing from explanations here?
It's not wrong, but it sounds a bit old fashioned. It's something you could write in a poem or when telling a story. That could be the reason why it sounds better in "Ulven spiser henne ikke" than in "De spiser måltidet ikke". The sentence about the wolf sounds like it's taken from a story, while the family eating the meal sounds like an everyday situation. It's correct, though.
Edit: It also works best when the object in the sentence is a pronoun and not a noun or a name. "De spiser det ikke." sounds better than "De spiser måltidet ikke."