I am looking for a hand held push alarm, any suggestions?

Hello, I am trying to find a hand help push alarm for my mother. She has ALS so the only thing that works on her body is her right thumb and right pointer finger. She currently dings a bell but its not that loud so I'm trying to find like a medical alarm or something. Ive googled and i've looked on ebay and I can't seem to find a PUSH button alarm. Any suggestions would be greatly appreciated