Lily's grandmother is a mentioned character in Fresh Beat Band of Spies.
In "Cute Crook," Commissioner Goldstar tells the Fresh Beats that Lily will be staying with her grandmother for the weekend. Lily later states that her grandmother is allergic to dogs, which is why she asks the Fresh Beats to take care of her pet Goldie. Lily's grandmother is possibly Commissioner Goldstar's mother, though it is never stated.
It is unknown what Lily's grandmother looks like, for she is never seen. However, she likely has dark skin like Commissioner Goldstar and his niece.
Lily's grandmother has never appeared in the series, but is mentioned in the episode "Cute Crook."