[HenryHuntington]

The 1956 PacTel Street Directory shows 6341 Yucca to be a dry cleaners and 6355 Yucca to be a florist shop with no 6343 listed at all. There are several apartment buildings listed in the 6300 block; so if Ms. Burnett was off on the street address or was misheard, did she say what her grandmother's last name was?

Update: Never mind, I found it: Mabel Eudora "Mae" Jones White, who passed in 1967 and so maybe still lived in Hollywood in 1956. No hits on Yucca that I could find, though.