Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
Performing prayer is one of the greatest pillars of Islam. One who gives it up, although he believes it is a duty, commits one of the major sins. Furthermore, some scholars believe that one who gives up the prayer just due to laziness is a true disbeliever. See our Fatwa 81555
As for Hijab, no doubt that it is a Divine obligation on women as proved in the Qur'an and the Sunnah.
Whoever abandons performing the prayer commits a major sin that is more serious than uncovering with Hijab, which is another bad deed.
The only solution is to perform the prayer, to wear the Hijab and to adhere to all teachings of Islam in word and in deed, Halal and Haram.
In addition, one has to know that a woman's prayer is not valid unless she covers her whole body during the prayer except her face and hands.
Allah knows best.