If you enter 'sunny' in the Send DU Mail to: text field and click the 'Find member' button, the result page should include a link to 'Show partial matches' - that will list all the sunny somethings. Hopefully something familiar will be in that list. Click on the usernames to go to their profile page - from the profile page you can click the Last post: link to read the most recent post made by that member.
I'm sorry to hear of the loss of your mother. My condolences to you and your family.