Veda has never been popular enough to be old-fashioned. Lovely that it’s a family name. It’s fairly uncommon but its style - V and vowel heavy, and 2 syllable (see Ava, Eva, Evie, Ivy, Ada etc) means she will still fit right in with her peers.
Rita is a dated nickname for Margarita that has yet to come back into fashion. Tbh imo it would be kinder to call her the full Margarita and let her choose the nickname. For a certain generation Rita is still “Rita, Sue and Bob too”.
Vivienne is quite trendy ever since Angelina Jolie used it for one of her kids - it’s more “French chic” like Isabelle, Amelie, Elodie etc rather than old-fashioned now. Vivian/Vivien (the English spellings) might be considered more retro.
Maud is now seen more as hipster cool rather than old-fashioned by younger folk imo. But unless you live somewhere like London, you’d likely still be one of the very early adopters as it’s definitely not Nancy or Mabel mainstream yet.
Personally I’d go for Veda.