How do I add quotes to xml result for a string value?

I am having trouble putting quotes around the following string value select statement in sql. How do I do it?

Convert(Xml, OM.Body).value('"(//DocumentResponseMessage/ecf:Document/ecf:DocumentMetadata/d:RegisterActionDescriptionText)[1]','varchar(250)"') AS 'CaseEventDescription',

The reason I need to do that is because the value has a comma in it and when I put the output in Excel, it is not fitting in one column. So putting quotes will help but I don't know exactly how to do it.
Kindly help.

It appears that you are trying to query an XML document, get the result of it, and then convert it to XML.I may have misunderstood the requirement. Sample data would help.

In any case, something that starts with double quotes is not valid XML. So if you want the result of the query to be wrapped in double-quotes, it has to be string - for example like this:

DECLARE @x XML = '<a>xyz</a>';
SELECT '"' + CAST(@x AS VARCHAR(32)) + '"';