As a starter, follow the directives and don’t hold an in-person meeting.  If you really need to meet, under your state law, and probably under the nonprofit corporation law of most states, you can hold a virtual meeting where the members can meet by telephone or other electronic means.  If you can’t get a quorum even then, your state law, and perhaps the state law of other states, provide that you can adjourn a meeting of members for a period of time and whoever shows up when the meeting is reconvened constitutes a quorum.  Legislatures have recognized that a lot of membership organizations have an unrealistic quorum requirement for membership meetings and that there has to be a safety valve when members don’t bother to participate.

The corona virus pandemic could possibly bring into play the emergency powers provisions of nonprofit corporation laws that were passed when the country was worried about nuclear war totally disrupting our society.  Your state law permits the board of a nonprofit corporation to adopt emergency bylaws to be effective during an emergency “resulting from an attack on the United States, a nuclear disaster or another catastrophe” when a quorum of the board “cannot readily be assembled.”   If you can’t get a quorum of the board, you could consider this provision of the statute.  I would be a little reluctant to utilize this provision if such procedures are not already included in your bylaws, but if events become significantly worse it is worth remembering that the potential exists.