I would assume that it's not theirs anymore? There is no way people comeback?
It's seemingly unlikely, at least for a good while. There's a rift through town and beneath it is a chasm. A few people, were allowed into town with supervision to get necessities from their homes and during that time the alarm sounded because lethal amounts of gasses were detected so they had to leave immediately.
Even with the best case scenario of the eruption being on the North-East side of Þorbjörn you'd still have lava and gasses come towards the town.
It's not unlikely that these ~3700 people will have lost their homes and the sports club of Grindavík will now be defunct. We'll see. The government has just implemented a 3 year tax that's going to cover the fees for a protective wall that's going to be built around the town and Blue Lagoon. Maybe that will partly solve the problem. In the meantime it will obviously impact a lot of people financially, solution will have to be made for around ~500 children with regards to schooling which is tough because the school infrastructure is already imploding (Iceland currently has the highest population growth in the world).
So a lot of problems that need solving quick, a lot of money needed and a lot of housing which is already the most expensive in the world.