If the husband was Thomas Young, then there's a fair chance that Ketrin Young was not his wife.
The custom of the wife taking her husband's surname did not come in from England until the 19th century, which is why you usually get the wife's maiden name in records like baptisms and legal documents, and on gravestones. You also get the wife's maiden surname in her death certificate after 1855, and the maiden names of the mothers of marrying couples in statutory civil marriage records
A married woman in the 18th century would mostly be known as 'Mistress xxx, wife of Mr yyy'.
So if you are looking for a mortcloth record of a married woman in the 18th century, you probably need to look for a maiden surname.
