My brother is POA and he brought my grandma home to take care of. But, he can't because he is disabled.

Did brother take her home primarily to have access to her money or use her monthly checks for his benefit? If so, that is classic elder abuse. APS should take grandma out of there and put her in a nursing home, and you should cooperate with them.

If that someone is not you who reported then you should also file a report

Has APS been there? If not, when they do come, make it clear that u only stepped in to care for GM because brother can't. That you feel GM needs to be placed.

Call 911 and get her a social admit to the hospital and then get her placed in a nursing home. You can’t care for her 24/7 by yourself. You would be enabling the situation to keep this going.

Call APS yourself and ask for help.

So is the main issue that he is disabled and can't really care for her? Is he mentally disabled?

Or is the issue whether there is financial mismanagement/abuse?

If you have actual proof, and you have another solution (ie. you want to be her PoA or legal guardian, or you are ok with the county becoming her legal guardian) then maybe retain an elder law attorney.

If the neighbor is going by only what your grandma is verbally telling them, this may not in fact be true or accurate. If she has dementia, paranoia and memory impairment causes those with dementia to have delusions and repeat confabulations.

So, if APS finds no actual proof (like seeing what's happening in her bank accounts) then you will need to investigate anything that Grandma tells you in the future before you worry or take any action.

You cooperate with APS to get brother removed as POA. You decide if you are ready, willing, and -- most of all--capable of being POA for your mother and if you wish to care for her 24/7. Then you work with APS to get this to happen through the courts.