Just in case breast feeding baby emergency if my 3 month old in an emergency can not nurse from mother what kind of milk would I have to buy that would not hurt her.

Any. Any infant under one year of age if not breastfeeding or drinking expressed breastmilk in a bottle should be supplemented with infant formula made for ages 0-12months. There are a variety of brands available for you to choose from. As long as it states its for infants 0-12months of age it will suffice. You can start with any milk based formula, and if baby has trouble tolerating it (diarrhea, increasing gas or fussiness) a soy based infant formula can be tried. In this case I would recommend to seek the advice of your child's pediatrician or family doctor. Remember breast milk is recommended for infants under 1, however that is not always possible, and formula is a great second choice. Keep up the good work mom!
Basic infant formula. Would be fine. Hopefully there is no significant emergency and this would only be a feed or two. It can be difficult to return to breast feeding once you've switched to formula.