Fndiz, it is indeed safe to travel to her home country, and return to the UK, as long as it is within the validity of her current DLR visa. According to the Asylum Policy Instructions (API/October 2006) on Discretionary Leave, Chapter 10 reads:
"A person granted DL will normally be expected to keep their own national passport valid. This is because we will usually not have accepted that a person has a fear of return to their own country or a fear of their own authorities and will have granted DL for reasons other than protection..."
My mate, like your wife, also came to the UK on a visitor visa some years back. She was later granted DLR, and went to her home country for a funeral. She returned via Heathrow without any problems at all. Infact, her Home Office letter (ICD.2155) states under the heading
TRAVEL ABROAD that,
"You may travel
out of the Common Travel Area (UK, Channel Islands, Isle of Man and ROI). On your return, you will be re-admitted to the UK without having to obtain fresh leave to enter unless
1. You have been absent from the UK for a continuous period of more than two years, or
2. You are seeking admission for a different purpose from the one for which this leave has been granted.
I hope that this clears up any doubts you might have had about travelling. Make sure that your wife also carries (in addition to her passport ofcourse
) her Home Office document and marriage certificate as back up, just incase the immigration officer decides to make life difficult.
My friend has since re-applied for an extension of her DLR, and was granted it without problems, even though her passport showed that she had gone back to her home country for a few weeks! So best of luck! You should be okay!