Is mom's caregiver taking advantage?

There are several red flags in your question. First, is that this caregiver may be privately hired, since if the caregiver is from an agency, then it is the agency's responsibility to deal with the caregiver, and not yours. Since it sounds as if this may be a privately hired caregiver, and if that is the case, then you or someone needs to be monitoring the care regularly and at sporadic times each week and each day. There needs to be a plan of care established, and the caregiver needs to sign off on that. Included in that plan of care would be activities, with a budget. And there should be a daily record of activities, including meals eaten, cost and what was consumed. You generally cannot ask a caregiver to bring their own food, or at least that is normally not done, as meal time is usually a good social time and a time for companionship. If you have hired someone privately, and you need assistance with planning the care and monitoring the caregiver, then you can hire a geriatric care manager www.caremanager.org to do that for you. What concerns me is that your mother may be taken advantage of in many more ways than just expensive restaurant meals if someone does not create a care plan with a budget, and then monitor and supervise the care. Especially since you mention "senility" telling me that your mother has some mental impairment. I question who is employing this person and if employment laws are being followed, and if proper checks were done prior to hiring. Again, many red flags in this question which tells me your mother needs some professional intervention about the care being provided, and it needs to be done soon.