I have personally seen patients dealing with this problem along with their loved ones that were the ones that brough the concern up to me. First of all, sorry to hear, second I know this is extremely difficult due to the lack of cooperation. I would make an appointment with a geriatric psychiatrist or a kind hearted primary care geriatrician. After the appointment is set I would reach out to the office to inform them of the situation with your mother so that they can participate in the plan of getting her to come in for a visit. I would simply tell your mother that its time for a check up and your doctor wants to see you, that they called and since it is a new year they have new things to discuss with you to keep you out of the hospital (or use whatever you know would motivate her to go in). Sometimes we feel as family we are misleading our loved one, but this is completely correct and justifiable as they do not understand the nature of their condition. If they are completely and utterly resistant to go in, then try to set a telehealth appointment initially to at least get it started, even if the encounter is mostly with you and the doctor and not your mother due to her state. She may have developed a medication side effect if she is on certain meds, or a true mental issue related to a psychiatric problem or even in some cases as consequence to certain medical conditions. Of course dementia can have many presentations and forms and this may also be the cause. The most important thing to start is getting some good primary geriatric care to assist. I know its hard, but search and due your due diligence. If all else fails and you fear she is at risk to harm herself or others you can consider a "baker act" through your local police department if that is a law in your state. I know this sounds drastic but there are certain situations where this is justified, and honestly its better to go overboard than to risk irreversible harm if that is the case. All that we do we should do out of love for our family member, though we may worry about what our family member will feel emotionally in the moment. I have yet to see a case where the family resents the act of love to the point that it causes separation. Rather after getting appropriate care the loved ones always show gratefulness. You know her best, so do not depend on the opinions of others, sometimes not even other siblings truly understand because they are at a distance emotionally, mentally, or physically and in effect can be blind to certain important changes or dangerous ones in our loved ones.