Hi, this is Jim, thank you for the question - I will do my best to resolve this quickly for you.
Sorry to hear of the issue. The MIB will only accept a claim if the other party has reported this to the Police. The MIB is a government body set up to compensate victims of uninsured or untraced drivers. So whether this lady's claim is accepted by the MIB remains to be seen. If your Mother was not insured and the MIB do not accept the third party's claim, your Mother would be liable for the property damage but only if it can proven she caused the accident.
If they do sue, she will receive court documents (a response pack) which she must complete and return to the court. It is a tick box exercise for the most part and there is a short section to write a defence which is easy enough though please feel free to come back to this site if you need any more help. A claim will also take 6-12 months to be decided at court. If she lost then she would get 14 days to pay the judgment before the claimant can enforce the order, and 30 days to pay in full before it is registered with credit agencies. The claimant cannot recover legal costs if they win, in a claim under £10K (a small claim), all they can claim are the court fees and interest. If she was unable to pay the full sum owed at that point she could also ask the court to pay by instalments (a simple form is sent in, form N245, and a fee of £50 unless she qualified for a fee exemption so if she is on a low income, have low savings or in receipt of benefits then she would qualify).
I can assist her going forwards if it gets to the point they issue a claim.
I hope this helps and answers the question which is easy to understand - please feel free to ask me anything else. I will reply as soon as I can to help with any further queries.
Thanks for using our services and have a good day,