Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
Neglecting Salah is a great sin; we seek refuge in Allah from that. If the wife is sure that her husband is neglecting Salah, then it is not permissible for her to keep quiet even if her husband forbids her to talk about it.
She must enjoin him to do good and forbid him from committing evil, but this should be with good manners and kindness and soft words. It is also possible for her to give him some booklets and tapes as presents, which talk about the danger of neglecting Salah and what Allah has prepared as punishment for those who neglect Salah.
This woman has to turn to Allah and ask Him to guide her husband to the straight path and render him righteous. The husband can also become righteous by approaching someone who could advice him and who can influence him, whether from his family or else.
We ask Allah to make your husband righteous, and to straighten the affairs amongst yourselves, and to make things easy for you and to choose for us and for you whatever is better for us.
Allah knows best.