need help with ella song during malcom x

The song is "Azure,' and you're correct, that's Ella singing.

"Azure" appears on the following albums (and perhaps others I missed) :

Ella Fitzgerald, "The Complete Ella Fitzgerald Song Books"
Ella Fitzgerald, "Best of the Duke Ellington Songbooks"
Ella Fitzgerald, "Ella at Duke's Place"
Ella Fitzgerald "Malcolm X [Original Soundtrack]"
Ella Fitzgerald "Sings the Duke Ellington Song Book"