Translation:This dinner is delicious.
Please let me clarify this: In this sentence, some kanjis are correct but not usually used. I think the most common way to write it is この晩ご飯はおいしいです。This is based on a list of "common Kanji" made by Japanese government but this list is just a suggestion. You'd better only use common Kanji and their pronunciation but you won't be punished if you don't.
Because it is wrong to do it that way. You should have a Japanese keyboard on your phone/computer by now, it takes less than 5 minutes with Google search to install.
この~, その~, あの~, and どの~ must be immediately followed by a noun. I include the ~ to show that they aren't complete without something following.
の is indicates possession and is in a sense like a particle. このabc would be "abc of this" e.g. この晩ご飯 "dinner of this" (it looks and sounds weird but that's the literal translation). If you stick a は/が after の then it'd just look and sound wrong. は comes after 晩ご飯 because it's a particle for the object (dinner).
Note: Some people use "supper" instead of "dinner," and some people also (confusingly) use "dinner" instead of "lunch," so it'd be nice if they added those to the synonyms of their respective dictionary words (I'm using a PC and I could mark a dictionary answer missing but there was no place to enter in WHAT was missing even after I clicked it, so I guess I just have to explain here?).
This and that are both pronouns and adjectives in English. In Japanese, これ is a pronoun, and この is an adjective. In your answer you used the pronoun form of "this"(これ) but the question used the adjective form of "this"(この). In Japanese grammar, この, その, and あの must always be right before a noun. So, the translation can only be "this dinner is..." and not "this is..."