我買咗間屋，連傢俬電器租俾人，點知火燭

Sorry about your loss.

There is no universal way to resolve your issue.

The solution depends on the cause of fire.

At this moment, I do not recommend a security deposit refund, as the tenants may be liable for the incident.

You should reply to the tenant in writing to preserve a record.

(Please note - it is possible that you may be liable for the tenant's loss as well.)