If number two does not work, then the facilitator should try to mediate the dispute outside the group meeting. It takes a great deal of prayer, patience and work from all parties, especially the facilitator, to bring peace. It is important to avoid bringing down the entire group when a conflict arises. The life of the group is really at stake. On the rare occasion a conflict cannot be resolved, it may be appropriate for some to leave the group.
Separation is better than having individuals destroy each other, spiritually or emotionally.
Those who do leave should be helped to find another group with which to meet. There is just something about our spiritual makeup as Christians that requires community. Hopefully option number four will be exception. Homogeneous churches lie totally outside Paul's frame of reference. After all, such churches cannot maintain the unity of the Spirit that either Ephesians 2 and 4 or 1 Corinthians 12 call for.