Mom won't take her antibiotics. Any advice?

She doesn't eat much so can't put them in food. Can't put them in juice--she sees it and refuses to drink it. She has a bad bladder infection--one she keeps on getting. Some days she is fine and will take her meds when I give them to her. But other days she is angry and belligerent and refuses to take them. I feel like I am on a roller coaster with her. She has undiagnosed dementia. I have difficulties getting her to the doctors too. I've had to cancel many, many appointments at the last minute because she refused to go--even telling her we were going shopping doesn't help. I'm trying to keep her out of a home but I am losing this battle. There are times when I have issues getting her up in the morning or getting her to bed at night. It is like she turns into this stubborn, angry, mean spirited person. I need help.