"We are fine."
There are different ways to say 'we are fine', this wasn't the one they were looking for. In your answer there's a slight error, as 'sisi' is plural it should be: 'sisi ni wazuri'. '-Zuri' is often used as a reply to 'habari', which then becomes 'nzuri'. Referring to people they often say: 'sisi ni wazima', or 'sisi wazima', or just 'wazima'.