The wording of your question is a little unclear, but I presume that you want to know how to ask whether a person prefers the title 'Ms' or 'Mrs'.
If in doubt, it is better to use 'Ms', as this won't be wrong. You could start by addressing her as 'Ms Smith', for example. She is unlikely to object to this, as it is fine to address any woman in this way. She may 'correct' you by saying 'Mrs Smith', or even Dr Smith or Professor Smith, if that's the title she prefers to go by.
She may also respond by saying, for example, "Call me Elizabeth". In Western countries, it's becoming more and more common to address people by their first names, even in business and relatively formal contexts.
As the only woman - so far - on this page, I would NOT recommend a direct question along the lines of "Is that Ms or Mrs ( or even the horribly outdated 'Miss!) ?" or even the less direct "What should I call you/How should I address you..Ms or Mrs?". It feels old-fashioned, intrusive and sexist. Why should my marital status be relevant? Why should you ask this of a woman or not a man? What's this got to do with you, anyway? What makes you think that these are the only two alternatives ( I could be a Dr, a Professor, a Reverend, a Councillor, a Senator) ?
Please take my advice : don't draw attention to your awkwardness about this question, as this will only create more awkwardness and may make the woman feel uncomfortable or even irritate her. Just call her Ms [+surname] (with a z sound). In conversation, especially with your non-native accent, 'miz' will sound almost identical to 'misiz', anyway. She may not even notice. It really is not something that you should make an issue over.