my mom who is ninety eight is in a care home I visit every night my sister said she is going to get her a wheel chair to take mom out my mother has vascular dementia and I am wored that it will frighten my mom she has only been out once in three years and she told me that she didn't like it my sister never informed me that she was going to do this
I'd keep in mind that if your mom is in a wheelchair, she'll need a van with lift or be able to have mom transfer from the car to the chair. That's a big risk for someone who is not used to this and a fall could cause a fracture.
When I moved my Dad into senior living, the only time he went out was for doctor appointments and a hair cut. I never even brought Dad back to my house and he never asked to go. He was very content being in senior living where he had his caregivers, Aides, and the confidence of knowing there is a nurse on duty all day.
You sister needs to read up on Dementia so she would have a better understanding. What might sound good and sweet to her, could cause a lot of confusion to the elder.