areas of similarity to my situation

since it isn't known whether the psych nurse ordered the meds or forgot, or whether it was the chemist - I would find a way to check about that. The nurse documents all actions in the patient's file, (phone calls, visits, whatever is done) - is there a supervisor that you can talk to.
The nurse very well may have called for the meds.
You can always go to a lawyer, or the licensing association to have them check the patient's file. They will do this.

But remember, your mother has to let the person in to her home. Don't blame the nurse if your mother won't let the person in.

Like in the case of my own mother, put on risperidone because of psychosis (not yet schizophrenia at that point, but who knows now, a year later) - she won't tell the doctor about her delusions, hallucinations, etc - because she's smart enough to know that if she does then they might not let her return home, so she lies to them. Then she comes and tells me all her delusions, etc. Then I end up writing it all down and delivering the information to the doctor so that he will know. Want to know what frustrating is? Partly, my disgust is that the staff of the health care team/system aren't able to develop a suitable relationship with her such that she would trust them, share her fears, and then maybe they could help her.

About groceries - some grocery stores deliver (just have to phone in the order) - for a fee of course, but in my area, the fee is only $5 for a delivery.

I left the situation because of all the nonsense - it's a long story. And her problems are returning to intrude in my life again. I tried. She won't listen. Was ruining my life. Yes, we have concerns about human beings. And we don't want harm to come to anyone. And we can see when someone is behaving irrational, and it gets beyond the person's control. And sometimes the crisis team has to be called. And then there's the other family member(s) who won't acknowledge that it's happening (thanks for nothing eh?)

oh, and when I would phone the mobile crisis people, they would say "phone the police or 911"
or, they would at least talk to her on the phone if I had to phone for help around midnight , but she wouldn't tell them the truth either, then after speaking with them, then she starts up again with the delusions, etc.

From my readings about this, sometimes the problems in older people can be imbalances re: their body electrolytes (such as too much calcium, or sometimes it's a potassium problem that causes psychosis, hallucinations, personality changes, confusion, sometimes it's specific medications, because an older person's liver doesn't metabolize like a younger person's liver, so active metabolites accumulate, or maybe kidney problems so the drug isn't excreted), and the way to find out is to have her serum electrolytes checked and her medication levels and interactions reviewed.

or maybe it's an infection (that'll sometimes contribute to this kind of problem)

or it could be something like sensory-perceptual (like having cataracts or hearing problems) - does she use a hearing aid? How's her vision?

I really do wish you all the best in this.