If it is homemade then it depends what you put in the soup.
There are hundred's of yummy syn free soups you can make and enjoy all syn free. Others may have a small syn value or only be free on certain plans.
Here is a link to some recipes if you are interested. xxxx
Stock cubes are syn free, so if it's just stock and free foods then it should be syn free.
If there's cream in it then you'd have to work out the syn value for how much went in, and then divide it between the portions, but it usually works out really low.