Dressing the mothers of the bride and groom can be tricky territory. They shouldn’t fade into the background in a beige suit, nor should they look like they’re trying to steal the spotlight. Plus, shopping can be a fraught experience for fifty-plus women, who have hard time finding things that aren’t either too young or too dowdy.
In my opinion, the mothers shouldn’t match their colours to those of the bridesmaids, and they shouldn’t match each other. White will look competitive, and black might be taken as a subliminal message about the union. Any other colour is fair game.
If the mothers wish to coordinate their outfits, etiquette holds that the mother of the bride choose hers first, then communicate what she’s wearing to the mother of the groom; then the mother of the groom can pick something of similar formality in a colour that doesn’t clash. It makes sense to give the mother of the bride the home-court advantage at a traditional wedding, where the brides parents are paying and hosting. But these days, everyone may just choose to go out on her own - it all depends on the dynamic. The most important thing is for the mothers to feel comfortable and attractive in what they’ve chosen; to some extent, they’ll be in the limelight on your wedding day.
As for exactly what to wear, many mothers lean toward structured suits in dressy fabric rather than dresses, though a dress with a matching, tailored jacket is also a nice option.
If you have time, helping your mother shop for her outfit can be a fun outing and a great bonding experience. Many bridal solons can styles for the mother of the brides, so if your mother is with you while you’re shopping for your wedding gown, have her try on some dresses, even if she isn’t ready to get serious about shopping. It’s a convenient way to open a dialogue about what you both like and think will work well.