Do the borrowing companies have a guarantor that will help mitigate losses for investors?

Take a look at their methodology in issuing the loans. Different companies have different methods to mitigate losses.

I remember Mininterst is compulsory to have a guarantor

For funding societies, it varies

Some loans have collaterals, some have their skin in the game. Not always transparent how much % the P2P companies chip in though. Taking it at face value.