Widowed guests

I read online that you use Mrs. because they are not divorced, just widowed so that's what I did

Ms. can be used for any woman--married, single, divorced, or widowed. That was in fact the whole point of it--to have a title like "Mr.," which you could use without needing to know someone's marital status.

If you don't like to use Ms., though, you'd use Mrs. for a widow. Traditionally, a married couple in which the wife changed her name is Mr. and Mrs. John Jones. A widow who uses her late husband's surname is Mrs. John Jones. (Her title doesn't change at all when she is widowed.) A divorcee who still uses her former husband's surname is Mrs. Susan Jones. And a single woman, or a married woman who did not change her name on marriage, is Miss Susan Smith.