The desktop site offers a link to "Create page on this wiki" when a search doesn't come up with a match. Mobile users should have that option too.
Location #1 (In search dropdown)
No pages with this title - Link: Create Page
Location #2 (After the search within pages is attempted)
"There were no results matching the query."
Why not be bold? Create this Page <--BUTTON
Further, even if there are a few matches related to the topic, the mobile user should be prompted at the end of the results list:
Didn't find what you're looking for? Create a page about it:
Name of new page: ___(Input Box)______ (create page button)
This will help drive new article creation even for established wiki's