I’m so sorry for your loss 
Both are beautiful options and I wonder if thinking about meaning might help here. [name_f]Zelda[/name_f] (grey warrior) offers strength and courage; [name_f]Zelma[/name_f] (“gods helmet”) may appeal more if you want that spiritual element.
[name_f][/name_f]Based on sound, the gentle yet solid feel of [name_f]Zelma[/name_f] appeals to me slightly more, but [name_f]Zelda[/name_f] is bright and memorable.
[name_f][/name_f]Some middle ideas:
[name_f][/name_f][name_f]Zelma[/name_f] [name_f]Louise[/name_f]
[name_f][/name_f][name_f]Zelda[/name_f] [name_f]Beatrice[/name_f]
[name_f][/name_f][name_f]Zelma[/name_f] [name_f]Carys[/name_f]
[name_f][/name_f][name_f]Zelda[/name_f] [name_f]Mabel[/name_f]
[name_f][/name_f][name_f]Zelma[/name_f] [name_f]Winifred[/name_f]
[name_f][/name_f][name_f]Zelda[/name_f] [name_f]Willow[/name_f]
[name_f][/name_f][name_f]Zelma[/name_f] [name_f]Penelope[/name_f]
[name_f][/name_f][name_f]Zelda[/name_f] [name_f]Amelie[/name_f]
[name_f][/name_f][name_f]Zelma[/name_f] [name_f]Felicity[/name_f]
[name_f][/name_f][name_f]Zelda[/name_f] [name_f]Mirabel[/name_f]