Hello,
We need our daughter to be able to disable the home alarm, but we’d rather not give her this possibility when she’s not near the house (home wifi).
We’d like her to be able to disable it via a virtual button i’ll put on her dashboard.
Any idea how to catch which smartphone it’s originating from ?
You can use e.g. conditional card , showing the button only when she is ‘local’ (you would need to know how to identify that too)
Conditional card - Home Assistant (home-assistant.io)
Or restriction card, e.g. you could have it use a pop-up requireing a confirmation first, or entering a (known) code.,…the latter I do use for my power switches which I donot want to accidentally switch off, the code is just a mechanism to slow me down 
iantrich/restriction-card: 
Apply restrictions to Lovelace cards (github.com)
Both only work on the front end, the entity itself remains open for change