Depends how she got citizenship. If she got it through bloodline, maybe you're eligible too. If not, you can come as a tourist. Probably 3-6 months, depending on country. May be eligible for cheaper visa if you'd supply an invite from her.

Keep in mind that major non-EU countries (US/CA/AU/etc) don't need visa for tourist stuff. You'd get a stamp at airport for x months and that's it.