بسم الله الرحمن الرحيم
(1) If she could not offer Asar and Maghrib in the state of semi-consciousness, it is better to pay fidyah of these two salahs on her behalf. And no fidyah etc is wajib for the salah of the period during which she remained unconscious for months.
(2) You may do Hajj-e-Badal on her behalf or send such a person on her behalf who has already done his Hajj, and is pious and God-fearing person and is able to execute all the rituals of Hajj on behalf of your mother completely, then it shall be better.
(3) Do visit the grave of your mother occasionally and supplicate for her forgiveness and also for her high ranks. Recite the Holy Quran, durood and offer nafl salah and do isal-e-sawab for her. Also send the reward to your mother by helping the poor, needy ones and by donating money to madrasa, mosque and religious affairs as per your capacity. Offer your salah with jamah, hold fast taqwa and piety. Pay the rights of others. In-shaAllah, your mother shall receive the pleasure of hereafter if you do these practices and her ranks shall be elevated.
Allah knows Best!
Darul Uloom Deoband