Is it obligatory to make up the missed prayers that were not performed at the end of the menstrual period, due to not knowing at the time the obligation of the last prayer or combining two prayers?

If a menstruating woman purifies herself after the time for 'Isha' (night prayer) has begun, she must pray 'Isha' and Maghrib (sunset prayer). If she purifies herself after the time for 'Asr (afternoon prayer) has begun, she must pray Dhuhr (noon prayer) and 'Asr. However, if she purifies herself after Fajr (dawn prayer), Dhuhr, or Maghrib, she only prays the prayer for which she became pure during its time, because it is not combined with a preceding prayer. This is the view of the majority of scholars, whereas Shaykh Ibn 'Uthaymeen holds that she is only obligated to pray the prayer whose time she caught. The more cautious approach is to act upon the view of the majority.