Preview looks like some photo MC may see in someones home. I doubt MC don't know how his mother used to look like, there is no way Neil don't have any photo of her.
Since Lynette mentions only two friends of her and some woman called Marion- (since DPC did the trick with breaking off in mid-sentence like this I am not sure it's her full name) I think you're right, it's her friends on the photo with her (maybe on their way to see that terrible movie
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).
But there is a question: who took the photo and how can MC may see it? I am almost sure he will see it (don't know why, call it intuition).