In the present situation, I feel making one year as no education year and asking the students to remain home and study last year subjects. Last year also no examinations were conducted. This year also same is the case. As such the standard of the students will come down and there will be a problem for these students throughout their education.
If not postpone the examinations for another 2 or 3 months and then start next year classes. The academic year may get delayed but there will not be any problem. This delay can be adjusted in the coming three or four years and can come to a normal schedule.