I need a quick translation for my grandmother

I am also looking for a translation. I am trying to write my grandmother in Yokohama. I want to say "To the moon and back" however I cannot get a proper translation from my father as he has lost much of his Japanese.

Probably you just want to say "very much"? If you actually say "to the moon and back", she will think you are very weird.

As Firas suggested, please give us the whole context. You cannot expect a proper translation without context. For example, do you want to say "I love you to the moon and back"? And are you a male or female, and what age range are you in?

http://ja.urbandictionary.com/define.php?term=I+love+you+to+the+moon+a...

I am a male and it was book we would read when I was very young. So I know it may not be a proper translation but whatever makes the most sense so that she will understand the reference. 'I love you to the moon and back' is the line I was looking for.

So did you read the book in English or its translation in Japanese? I tried to find the Japanese title but cannot find it. If it was a book in English, then it would be better to write the English title as it was, otherwise she might not recall it.
If, however, she read it to you in Japanese, you COULD possibly try writing "Anata ga totemo daisuki" (I love you very much) or "Anata ga totemo taisetsu" (You are very precious)" and add "ano shirokuma no oyako mitai ni" (Just like that white/polar bear parent & cub), if you want to make a reference to the book.

"I love you to the moon and back" as a phrase itself is an idiomatic expression, that it needs to be paraphrased like I did above. So unless someone can find the title of the translated book (if any), this is the best (at least) I can do.

I gather that "from the moon and back" is not the title of the book you used to read but just a quote from the book.

Either way, as suggested, if you were reading it in English, then you need to write it in English so that your grandmother would recognize it.

If you want to write Japanese as a gesture of you honoring her culture, then write the English (so that she would notice that it's a quote) and write the Japanese translation next to it (to honor her culture).

In that case, the translation will be coming out of your mouth, so I would prefer something like...

o-baa-chan ga dai-suki dayo.

... which literally translates as "I love you grandma." in a boy-ish tone.

Or you can write something like...

o-baa-chan ga dai-dai-dai-dai-dai-suki!

...which will emphasize the greatness of your love for her.

Oh there is a kid's picturebook with that title, so I assumed the OP was talking about that. Sorry if I got that wrong.