The best graph option to display Flores del Mundo’s membership trends over the course of the year is a line graph with a data point for each month of the year (months on x-axis, # of members on the y-axis). A line graph would most clearly allow a reader to see trends over time compared to others displays.
If graphing total membership for the year stratified by member type (employee/spouse/dependent), but are not interested in seeing changes over time, I would use a bar graph, with each bar representing the total number of each member type. The different lengths of bars would make it easy to take away which member type had the most representation versus others during the year displayed. If you were interested in stratifying by member type and change over time, you could display the breakdown of member type for each month or quarter of the year.
If I wanted to display Eastern and Northern membership on the same graph and wanted to see trends over the year, I would create a line graph, similar to the overall membership line graph, but with one line representing Northern membership and another representing Eastern. I would be sure to have each line either be a different color or pattern for people to interpret clearly.