I can't edit my comment on mobile, but I read the comment section and it says this phrase is a shortening of "нет ничего хорошего", and нет calls for the genitive case here. As for the English translation, "nothing good" seems best because it retains the colloquial speech, but I don't see why yours shouldn't be accepted.
As important as the period is the capitalization of Ничево. In other exercises, people were marked wrong for capitalizing phrases, because the phrases were not sentences. The lesson: If the first word is capitalized - and it ends in a period - then the words form a sentence, which a verb (and in English a subject).
I reported it. 24 Dec 2018
Okay, I have a question, why is "good" in the genitive case here? This is really weird. There is also something I've heard somewhen that says "всего хорошего" and I have no, but not a single, not even the smallest bit of idea why are both words in the genitive case. Can someone please enlighten my understanding :P ?
This phrase is an abbreviation of "(Нет) ничего хорошего" (pay attention to the double negative)
"Нет" (There is no) takes the genitive.
"(Я желаю тебе/вам) всего хорошего" is another case. Желать, ждать, просить, требовать, хотеть, искать, etc all can be used either with the genitive or accusative, depending on level of object distinctness, abstractness and particularity:
- ждать звонка́ (gen.) - to wait for a call
- ждать звоно́к (acc.) - to wait for the (particular) call
- искать сча́стья (gen.) - to seek (my) fortune
- искать таре́лку (acc.) - to look for the plate
Because хорошего is in what's called the partitive case, represented by the genitive. The way to look at it is "nothing of good", i.e. no part of the good. It's used a number of languages, though by different means. An English usage could be: Three of the boys are tall. It essentially denotes a part, or some amount, of something.
"Nothing good" is actually a sentence commonly used in English. For example, "What's the word?" "Nothing good." Sentences in English do not always need a subject-verb structure, else "No" and "Yes" would not be complete sentences on their own (which they are). No further translation is needed.