In your MLA Works Cited list, dates are always written in day-month-year order, with the month abbreviated if it’s five or more letters long, e.g. 5 Mar. 2018.
In the main text, you’re free to use either day-month-year or month-day-year order, as long as you use one or the other consistently. Don’t abbreviate months in the main text, and use numerals for dates, e.g. 5 March 2018 or March 5, 2018.