She should wash it; in case mark is not removed she should change it by applying some yellow color. I had three menstruations together while I lives with the Messenger of Allah ﷺ, but I did not wash my clothes.  

حَدَّثَنِي أَبِي حَدَّثَتْنِي أُمُّ الْحَسَنِ يَعْنِي جَدَّةَ أَبِي بَكْرٍ الْعَدَوِيِّ عَنْ مُعَاذَةَ قَالَتْ سَأَلْتُ عَائِشَةَ ؓ عَنِ الْحَائِضِ يُصِيبُ ثَوْبَهَا الدَّمُ قَالَتْ تَغْسِلُهُ فَإِنْ لَمْ يَذْهَبْ أَثَرُهُ فَلْتُغَيِّرْهُ بِشَىْءٍ مِنَ صُفْرَةٍ قَالَتْ وَلَقَدْ كُنْتُ أَحِيضُ عِنْدَ رَسُولِ اللَّهِ ﷺ ثَلاَثَ حِيَضٍ جَمِيعًا لاَ أَغْسِلُ لِي ثَوْبًا  

[Machine] "Abdus Samad, the grandmother of Abu Bakr al-Atqi, narrated from Muadhah who said: I asked Aisha about the menstruating woman, does it stain her clothing? She replied, "I used to have my menstruation when the Messenger of Allah ﷺ was alive. I had three consecutive periods and I did not wash any of my clothes. She also said, "The Messenger of Allah ﷺ used to pray while he had a garment on and some of it would touch me, while I was menstruating and sleeping close to him."  

عَبْدُ الصَّمَدِ وَهِيَ جَدَّةُ أَبِي بَكْرٍ الْعَتَكِيِّ عَنْ مُعَاذَةَ قَالَتْ سَأَلْتُ عَائِشَةَ عَنِ الْحَائِضِ يُصِيبُ ثَوْبَهَا الدَّمُ؟ فَقَالَتْ لَقَدْ كُنْتُ أَحِيضُ عِنْدَ رَسُولِ اللهِ ﷺ ثَلَاثَ حِيَضٍ جَمِيعًا لَا أَغْسِلُلِي ثَوْبًا وَقَالَتْ لَقَدْ كَانَ رَسُولُ اللهِ ﷺ يُصَلِّي وَعَلَيَّ ثَوْبٌ عَلَيْهِ بَعْضُهُ وَعَلَيَّ بَعْضُهُ وَأَنَا حَائِضٌ نَائِمَةٌ قَرِيبًا مِنْهُ