One of the many questions with no definitive answer!! You are trying to put rational logical cause and effect on a situation that is irrational. Mom's melt downs after you leave may or may not have anything to do with your visit. I would suspect it is caused by sundowning and not by something you are doing. That is the time of day when they are the most confused. Your visits may be delaying the melt down and actually making it better (or at least shorter). You may very well be her security. But she may be distressed because you are gone. It's not dependence as much as just knowing you are no there.
As for the care givers calling you in the morning... is this a facility that is trained in dementia care?... or just regular hospital staff? If they pop in on Mom, she's not ready to cooperate, and they push her, she is going to rebel. If they continue once she is upset it is only going to get worse. They say Mom is being feisty when in fact that don't have a clue how to deal with her and it is their problem not Mom's. She's reacted appropriately related to her dementia.
They should go in up beat, not in a hurry, talk to her, let her know what they are going to do, and try to involve her in her care based on her abilities. If she refuses, back off and try again later or with another care giver. Never demand or become hostile with them. If they get in a fight with dementia... they will lose! ... or you will end up there
Mom's caregivers know not to wake Mom up. As soon as she gets up, they give her medication. Then they give her about 20 minutes to adjust to being awake and the meds to take effect. Then Mom's favorite care giver goes in and coxes her through her morning routine. Works every time. But if they shake her and wake her and start ripping off her clothes she will fight them. Wouldn't you if somebody you didn't know came in and started undressing you? They can not explain to Mom what is happening because she can not process what they are saying like a mentally alert patient. Untrained staff doesn't understand this difference.
So you probably need to look a little deeper to figure out what is going on
Don't blame it on your visits or Mom's temperament until you know the before and after and what happens if it is different.
What you can't do is take a guilt trip. Guilt is reserved for a time when you deserve blame. There is no way you deserve the blame for Mom's acting out, her temperament, the inability of staff, or because she has a brain disease. You are doing the best you can in a bad situation. That is all anybody can ask of you so leave the guilt trip for those who need it