If we are talking about the British Red Cross Medal, you can use:
{{Medal
|medal=British Red Cross
|image=McKersie-22-1.jpg
}}
If you just mean the organization in general, you can use the following, but you would need to source an image of the Red Cross that is not under copyright or protection under international laws:
{{Occupation
|image= ???
|text=was a member of the Red Cross and nurse at the Moat House, Soham
}}
