You will be aware that redundancy can be complex. Redundancy is when you dismiss an employee because you no longer:

• carry out the business for which they are employed
• carry out the business in the place where they are employed
• require them to carry out work of a particular kind.

For a redundancy to be genuine, you must show that the employee's job will no longer exist. Redundancy is one of the fair reasons for terminating employment but to avoid claims for unfair dismissal or discrimination you must follow a fair redundancy procedure.
 
Although a business will generally dismiss employees for reasons of redundancy as a last resort, this is not the case in every circumstance, and it is possible that subcontractors can be retained when employees are made redundant.  But each business situation is different and you need strong business justification for keeping the subcontractor rather than the employee – this is not simply reliant on the number of hours they work. It could be that there is a cost implication, or it may be that the subcontractor’s skills are used in a different job role to the employee, or other reasons.  Your question does not expand on the full situation and it would be wise to seek professional advice.
 

See also: Making staff redundant