Words that are made plural by a variation in spelling rather than by adding an -es or -s, e.g., women, men, children, people, should be treated as singular words when making them possessive.

For example:

The store is very pleased with its remodeled women’s clothing department.
There is a new children’s museum opening this weekend.
What are people’s favorite menu items?
All the men’s golf clubs are in this aisle.