I appreciate the complexity of the situation but C's interpersonal skills are so poor, they make matters worse.
In her shoes, I'd be ensuring you stay on. That would take the form of listening, accepting your opinion, then resolving problems together. Eg fewer chickens and proper rat proofing so feed can be left out 24/7 in a hopper. Then your job would be treats, fresh water, free ranging time, health checks, and evening lock up. Her's would be eating the eggs whenever she wanted.
At least the fewer chickens part is happening.