Exposed filter in views to filter users by age
You can use the contextual range filter module. to create a filter range for your age field.


  Views Contextual Range Filter is a simple plugin for Views that adds
  the option to contextually filter, not just by a single value, but
  also by range.
  
  Numeric, alphabetical (string) and list ranges are all supported. Node
  ids, user ids and even taxonomy term ids are all special cases of
  numbers so will work also. Range-filtering on the "created" (posted)
  and "updated" (last modified) node properties is also supported,
  provided you use the correct format as dictated by Views. So, YYYYMMDD
  for full dates or one of the shorter year+month, year-only,
  month-only, week-only and day-only formats.