88 yr old mother is confused and barely mobile. Brother who is caregiver plans to take her on family's winter vacation. Isn't she too vulnerable?

She certainly is. You can expect that her confusion can get worse during a trip. On the other hand, your brother needs some vacation. Could you substitute for him and take care of your mother while he is away?
This depends. On condition of caretaker1! she needs almost constant attention!-ck with her pcp.