In Views, use group type's image in a field when a group content type is fitered
You will need to setup a relationship between the "Group Type" and "Group Content" content types. If the parent > child relationship is determined using Taxonomy you can use the "Taxonomy: Parent Term".

Then you can add the field for the image which comes from the parent (make sure you change the relationship to the parent tax) and have it on the same row the as children.