Sadly this young lady has no legal status to remain in the United Kingdom, I am sure after a reasonable period, she would be required to leave the UK and return home, the basis of her visa is that of a marriage, which due to the unfortunate demise of the intended spouse, this did not happen, the rules are the rules one is duty bound to say.
However, I wish her well, I am sure in time, she will find a new partner, and begin the process again, our condolences to the lady concerned.
