The friends bid on it simply so one could give it to her, via the Tenant system.

The ones who don't care about owning a house step in and try to buy it, then pass it off.

So a friend bought it, made the one who actually wanted it a Tenant along with their partner, since it's now listed as "X and X's House" on the Placard, neither of which was the actual owner.

As a tenant they can do the following:
Customization - Adding / Removing / Dyeing Furnishings
Gardening - Planting / Harvesting / Crop Disposal
Stable Tending - Stabling Chocobos.
Orchestrion - Orchestrion operation

So, in short, that is what happened. She got multiple friends who came in that didn't likely care about owning their own house, instead having an Apartment and/or FC room, that stacked things in her favor, and the winner simply made her a Tenant with full access. So in essence, it's "her" house now.

It's why Housing is such a BS system right now.