Is Dad and Johnson the same contact (by commlink ID?).
For the most part, it seems like a pretty free-form code. You ask if she got the shipment, disguising it as something innocuous. Flowers, invitation. This last week we didn't ship anything, so even if there is some actual meaning to the word choice, it doesn't matter. The last message seems like something changed. I wonder if the first two shipments were a sort of test before being able to meet the Johnson himself (Dad) and go for the main prize. Or perhaps only the flowers were a shipment, and the invitation was an actual invitation - perhaps to take part in this job.
So, my guess is that Mom won't be expecting to hear from us as she would likely know that we stiffed the Johnson. Or she's dead if she was our go between and the Johnson included her in his vendetta against us. Assuming Mom is actually a she. So, we can at least attempt contact and see if we hear back.
So, the Johnson screwed us. How? Did we not know what the weapon was? Did he infect us? Is payment perhaps blood instead of money in order to slow the infection, similar to what Katsina (and maybe Ace) was likely doing with the blood in her fridge? Lots of unanswered questions, to be sure.
So, if we do decide to talk to Mom, what do we say? Assuming the code is mostly inferred rather than predetermined, we have to figure out what we want to ask. Maybe "Is Dad mad?" to see if she was party to the current job involving the artifact. And assuming that "Dad" refers to the Johnson.
In essence, regardless of who Mom and Dad are and their relationship to this job, we should decide what we want to say, then just make it oblique.
ETA: Does Gift Shop have a physical address attached?