JSFiddle - React, Tailwind, and code Playground

JavaScript

var data = {"people": 
   [{"male": [
     {"name": "Bob" ,"age": "32"}, 
     {"name":"Mike", "age":"22"}
    ]}, 
   {"female": [
     {"name":"Jessica", "age": "24"}, 
     {"name":"Ann", "age": "23"}
   ]}]};

function getMaxAge(array) {
  var max = 0;
  array.forEach(function(people) {
    if (people.age > max) max = people.age;
  })
  return max;
}

var max = 0;
var arrayWithMax;
for (var i = 0; i < data.people.length; i++) {
  var array = data.people[i][Object.keys(data.people[i])[0]];
  var currentMax = getMaxAge(array);
  if (currentMax > max) {
    max = currentMax;
    arrayWithMax = array;
  }
}

console.log('max age: ' + max)
console.log(arrayWithMax);