If they get offended because you didn't read their mind to know which they preferred, they are obviously extremely unreasonable and probably looking for a reason to be offended. So they'd be offended and aggressive whatever you did. If you could somehow read their mind, they'd have been offended at your intrusion. Even if you ask, they'll probably be offended.
Personally, I'd ask. It usually means that I have to explain the options to her, which always strikes me as weird. How could any adult not already that there are three standard formal means of addressing a woman and no way to determine which one applies?
Or you could refuse to use any of the standard forms of address (Mr, Mrs, Miss or Ms) on the basis that they are archaic references to extreme classism, serfdom or even slavery, and you do not wish to adopt such an extremely inferior position or perpetuate those things in any way. Mr is an abbreviated form of Master and the others are abbreviated forms of Mistress. Mistress as in owner, not the more recent meaning of someone a married man is havig a long-term affair with.
Or address everyone as Doctor, on the basis that people are unlikely to be offended by being addressed that way.