Jill's mother is called Amelia (seen in the episode with the flashback of Jill and her sister).
Lynette's two friends are called Viviane and Miranda. So not Jill's mother.
However, the house in the photo is the same. The less far-fetched theory is that one of the two is a Royce (Vivianne or Miranda), possibly a sister of Amelia, Jill's mother.
Apart from socially situating Lynette's family in the Royce circle, it may later explain how someone from the Royces (Jill, or her mother) made the link between the MC and Lynette's family, thus allowing the MC to meet them at last.