My Mothers date of death was May 23, 2019. Please confirm when the end of the 11 months of kaddish would be. Thank you

ב"ה Shalom, The 23rd of May 2019, was the 18th of Iyyar which was Lag b'omer, the 33rd day of the counting of the Omer. If your mother died on May 23rd before sunset , Kaddish is to be said until (and including) the 17th of Nissan , which this year falls out this year April 11, Shabbat, the third day of Pessach Besorot Tovot A very happy and healthy Pessach.