Concerned about sudden possible mental illness.?

So my grandma is 89 and she’s been living with my mom and I for almost 2 years since my grandpa died. She doesn’t do much usually scoots about the house usually talking to her friends in the phone and watching her soap operas. But she refuses to leave the house because she’s afraid of falling which at her age is understandable. However over the last week she’s been acting alarmingly weird. She’s been sleeping in the middle of the day all day. She has a tv in her room that’s usually on 24/7 and when she wakes up she keeps hallucinating that someone is in her room trying to get her or her friends are there or she just talks to herself. She’s not eating as much as usual either. She has hear problems controlled by meds and arthritis and that’s it nothing mental. She just had a check up last month and they ran tests nothing came back in her blood. I’m not sure but something is wrong and I don’t know what it is. She’s been talking to herself all day today in between sleeping and even called 911 and yes the police showed up! Like I don’t know what to do. She’s not showed signs of dementia until now and we have had her tested as a precaution.