If wifes mom had it is it possible that she will have ovarian cancer?

Yes.. there is: A genetic risk with brca-2 for both ovary and breast cancer. However, a case does not establish the genetic link, genetic testing is needed. It would be importnt not only for your wife, but her sister, and their and your children.

Possibly: There is an increased risk of ovarian cancer in family members: this is the reason for taking a history. However, just because your mother-in-law had ovarian cancer does not mean your wife will also develop ovarian cancer. The risk increases as more members of the family are affected (siblings, aunts, daughters), so gynecologic exams or ultrasound can be used to help with screening.

Possible: Majority of ovarian cancer is sporadic. However, there is a familial type of ovarian cancer- i.e. Ovarian-breast hereditary syndrome- where people can have mutation in the brca 1/2 genes.It will give her significant risk to develop both ovarian & breast ca as well as other cancer. Check if there's other family members with different kind of cancers.She needs to discuss with her doctor her risk.