Display hierarchical entity reference fields inside node
You could render this with four different display modes:

1.) The Event view mode to start with:


Event Title
Event Date
Event Description
Reference field for Organization, configured to render the view mode logos1
Reference field for Organization, configured to render the view mode logos2


2.) The Organization view mode logos1 contains one field for the Organization logos:


Image field logos


3.) The Organization view mode logos2 contains one field for the User logos


Reference field for the content type User, configured to render the view mode userlogos


4.) The content type User view mode userlogos


Image field for user logos


To implement two instances of the reference field you need the module Display Suite. Or combine logo1 and logos2 in one view mode with two fields, but then the logos will get mixed. Or use for the second reference field a View, with the help of EVA.