I have fairly small eyes (medium sized for being East Asian, small compared to most.) You can wear black eyeliner and wear it normally, you just don't line your entire lid. I usually line the top part entirely and the outer 1/3 to 2/3 of my lower.
What does her dress look like? I've been doing the smokey lid thing with taupes, coppery browns, and other medium dark shades. Dark colors, in an overwhelming amount, can shrink the eye. I'm also just over black smokey eyes and like to experiment more. Gray or lilac could also be very pretty.