Who determines how to do the work during the Sprint?

How often should Development Team membership change?

Cross-functional teams are specialized for working on specific system components (e.g. design, database, backend, frontend).

Every Development Team should have the competencies and skills needed to deliver a Done Increment in a Sprint.

During the Sprint Review, one of the stakeholders announces that due to recent market changes, there is risk that funding might be reduced for the project. This triggers tensions to rise and arguments to break out between members.
As a Scrum Master, what would be the best two actions to take? (Choose two.)