Too bad, Jelder. The inhospitable Tasmanian snow sleet hail and frost has probably cryogenically preserved those few bees. It has always amazed me that your patch of frozen tundra can support any life..
Had the colony been viable I would have suggested boxing them ASAP and moving them to Queensland to thaw out. I don't think it would take much to knock an external colony in winter there.
Are you on a swarm catcher list there? You might find a few swarms around when Spring comes.