What is the ruling for a widow going for 'Umra during her waiting period?

A widow who is not pregnant is to observe a waiting period of four months and ten days and nights.

Allah Almighty says:

And those who are taken in death among you and leave wives behind – they [the wives shall] wait four months and ten [days]. And when they have fulfilled their term, then there is no blame upon you for what they do with themselves in an acceptable manner. And Allah is [fully] acquainted with what they do. [Quran 2/234]

The meaning of 'they [the wives shall] wait' in the above verse is that widows are not to marry during this period nor do anything that contravenes the conditions of the waiting period. The majority of scholars from among the Hanafis, Shafi'is and Hanbalis maintain that it is impermissible for a widow in her waiting period to go for Hajj or 'Umra because these rituals, unlike the waiting period which is time restricted, can be performed in the future.
The Ruling

It is impermissible for a widow in her waiting period to go for 'Umra.

Allah Almighty knows best.