A C2 is a tax clearance certificate meaning the builders tax affairs are up to date.
A homebond is an insurance bond covering certain structural defects and payments for up to 10 years. It is generally used in cases where the builder goes into liquidation and you then find you have a structural problem or your house is not completed. It has many exclusions and you should read up on the homebond guarantee before you think it covers everything. It does not. Furthermore it is dependant on the work of the builder being up to scratch on their inspections ( homebonds) which is not always the case. Google homebond- they have a website.