When you went in to make your deposit, the bank representative said the amount of

Nancy will prevail as she has used the property, openly as hers for over 15 years.

Explanation:

Since in the question it is given that nancy would prevail as she is able to used the property and for her it is open for above 15 years

Also the conditions related to the  adverse possession would be fulfilled

So as per given situation, the above represent the answer

the same would be relevant