Q: How to arrange a meeting where there are attendees who have a history of conflict?
A: If it is necessary to invite people with a history of conflict, you would be advised to understand why their relationship is strained. Understanding their mutual conflict might well suggest a solution for how best to hold the meeting.
You may need to discuss the problem with them both beforehand (probably separately) in order to broker a tolerable way of working together at the meeting. You may also need to confront them about their behaviour, but this is only worth trying if you think that they have an interest and desire in resolving their differences.