The "ha" in front of "lailah"  is the ordinary definite article, even though the expression itself has a special meaning.
Like any other definite-article "ha," it should not be filed under.  If it is the first thing in a 245, the indicators should be set to 13, and if it would be the first thing in a uniform title, it should be omitted.

The interrogative "ha", on the other hand,  is retained and filed under and capitalized if it comes first in a title.