I am sorry, I didn't get how did you understand these are to be done after the death of prophet.
These are general commands to prophets SAW's wives, which are to be done always, not just after his death. And these are applicable to not just them, but all women.
Coming to your specific question about abiding in the house, It doesn't mean that they should always sit inside their home. It means they should not go out in the middle of men like women during the period of ignorance did. If they have a purpose to go out, they can go. A good explanation is given in Tafsir Ibn Kathir (copied from here):
These are the good manners which Allah enjoined upon the wives of the
Prophet so that they would be an example for the women of the Ummah to
follow. Allah said, addressing the wives of the Prophet that they
should fear Allah as He commanded them, and that no other woman is
like them or can be their equal in virtue and status. Then Allah says:
﴿فَلاَ تَخْضَعْنَ بِالْقَوْلِ﴾
(then be not soft in speech,) As-Suddi and others said, this means, do
not be gentle in speech when addressing men. Allah says:
﴿فَيَطْمَعَ الَّذِى فِى قَلْبِهِ مَرَضٌ﴾
(lest he in whose heart is a disease should be moved with desire,)
means, something unclean.
﴿وَقُلْنَ قَوْلاً مَّعْرُوفاً﴾
(but speak in an honorable manner.) Ibn Zayd said: "Decent and
honorable talk that is known to be good.'' This means that she should
address non-Mahram men in a manner in which there is no softness,
i.e., a woman should not address a non-Mahram man in the same way that
she addresses her husband.
﴿وَقَرْنَ فِى بُيُوتِكُنَّ﴾
(And stay in your houses,) means, stay in your houses and do not come
out except for a purpose. One of the purposes mentioned in Shari`ah is
prayer in the Masjid, so long as the conditions are fulfilled, as the
Messenger of Allah said:
«لَا تَمْنَعُوا إِمَاءَ اللهِ مَسَاجِدَ اللهِ وَلْيَخْرُجْنَ وَهُنَّ
تَفِلَات»
(Do not prevent the female servants of Allah from the Masjids of
Allah, but have them go out without wearing fragrance.) According to
another report:
«وَبُيُوتُهُنَّ خَيْرٌ لَهُن»
(even though their houses are better for them.)
﴿وَلاَ تَبَرَّجْنَ تَبَرُّجَ الْجَـهِلِيَّةِ الاٍّولَى﴾
(and do not Tabarruj yourselves like the Tabarruj of the times of
ignorance,) Mujahid said: "Women used to go out walking in front of
men, and this was the Tabarruj of Jahiliyyah.'' Qatadah said:
﴿وَلاَ تَبَرَّجْنَ تَبَرُّجَ الْجَـهِلِيَّةِ الاٍّولَى﴾
(and do not Tabarruj yourselves like the Taburruj of the times of
ignorance,) "When they go out of their homes walking in a shameless
and flirtatious manner, and Allah, may He be exalted, forbade that.''
Muqatil bin Hayyan said:
﴿وَلاَ تَبَرَّجْنَ تَبَرُّجَ الْجَـهِلِيَّةِ الاٍّولَى﴾
(and do not Tabarruj yourselves like the Tabarruj of the times of
ignorance,) "Tabarruj is when a woman puts a Khimar on her head but
does not tie it properly.'' So her necklaces, earrings and neck, and
all of that can be seen. This is Tabarruj, and Allah addresses all the
women of the believers with regard to Tabarruj.
﴿وَأَقِمْنَ الصَّلَوةَ وَءَاتِينَ الزَّكَـوةَ وَأَطِعْنَ اللَّهَ
وَرَسُولَهُ﴾
(and perform the Salah, and give Zakah and obey Allah and His
Messenger.) Allah first forbids them from evil, then He enjoins them
to do good by establishing regular prayer, which means worshipping
Allah alone with no partner or associate, and paying Zakah, which
means doing good to other people.
It is clear from the explanation that they can go out for a reason, but of course, when they go, there are conditions like hijab and all.
And it is also clear from the hadeeths that women went to masjid for prayer, came to prophet for learning and clearing doubts etc. (If you want, hadeeths can be added, let me know).
