I have said it before and I will say it again. Leave the reader with a good ending to your story. It’s not going to be a twist then give them a great last sentence. Having a great last line in your story is a win for the reader and it’s also a win for you.
More famous endings from great stories:
“So we beat on, boats against the current, borne back ceaselessly into the past.”
The Great Gatsby, F.Scott Fitzgerald
“After all, tomorrow is another day.”
Gone with the Wind, Margaret Mitchell
“He turned out the light and went into Jem’s room. He would be there all night, and he would be there when Jem waked up in the morning.”
To Kill a Mockingbird, Harper Lee
I know it’s easier said than done, but the last sentence is just as important as the first sentence. As a flash fiction writer you’re a fine craftman so give the reader your best work right until the end.