That's a specific issues order that I referred to previously, to get the court to order that British passports cannot be obtained without a further court order. See my previous response about that, it still holds. A MIAM is required for EVERY C100 application UNLESS you meet one of the exemptions on the form.
However, in relation to having the children returned to India, you need to report the abduction in your own country - and my understanding is that the parent with the children in their care in India is free to remove them from the country if they want to - i.e. in India it is not a crime for a parent to do that. It is a crime in the UK, but since the act didn't occur here and India is not part of the Hague Convention, you may struggle to get the children returned.
That said, I would suggest you initially contact ICACU - which is the unit that deals with child abduction in this country. As above, India is not on the list of countries, but given that the mother and children are here, they may be able to assist you. See the link below for the application form and the guidance notes for completing it - read it thoroughly.
I would also strongly suggest that you instruct a solicitor - solicitors.lawsociety.org.uk