If you are using "Mrs.", you must use the husbands name:
Mrs. Harold Happy NOT Mrs. Jane Happy
If you don't know the husband's first name, then use:
Ms. Jane Happy
When addressing an envelope to a recent widow, it is customary to write the person's name starting with the title "Mrs.". Just because a woman is a widow does not mean that a woman is not still married.
Address it as 'Pastor---(the name of the pastor).
In this wonderful modern age you can simply write her name on the envelope. It doesn't need to label her as married, unmarried, engaged, solo, etc. For example: If the person's name is Giselle Renoir and you want to invite her to a party then simply address the envelope to Giselle Renoir at her address. If you want to invite her husband too then simply address it to Giselle and Pierre Renoir.
Same as to anybody else. Put the name and address of the person clearly in the center of the envelope.
Ms. and then your last name.
You can address it to only one, or address it to both using both names. Either way is acceptable.
You can use Mrs., Miss, or Ms., depending on the marital status and preference of the woman.
Addressing an envelop to a woman with a boyfriend and young son: Just address the envelope to: Ms. Jane Doe & Mr. John Doe (if the young son is in their teens, but not necessary if they are a minor) & Mr. John Smith. So the envelope may read: Ms. Jane Doe & Mr. John Smith.
The correct way to address an envelope to a married couple that have different last names is to use both of their names. For example, you could write Mr. Johnson and Miss or Ms. Dwyer.
Frau
Madame.
"madame"