Is there such a device that when my Dad goes upstairs to bed and my Mom is still downstairs. If she would need his help for any reason (falling mostly) but is there anything where she could wear or clip on such a button and push it that it would wake my Dad up with an alarm sound or some schrelling sound that would alert him that she needs help??
Your situation is a little unusual in that it is the parent who is in bed who is "monitoring" the parent who is up and moving about.
A cell phone might be an option. I got my husband a very simple-to-operate model (Jitterbug) and programmed in our home number and my cell phone number. Would Mom be able to carry a cell phone on her when Dad goes to bed, and if she needs him call him on the phone? Is there a phone next to his bed? If they already own and know how to use a cellphone, that seems like a straight-forward plan. If not, is Mom's cognition OK to learn to use a simple cell phone with pre-programmed emergency numbers?
I hope you work this out. Please come back and tell us what you try, and what works best. We learn from each other.
I have also heard of using a walkie talkie set. I use the wireless doorbell too. I have the chime in my room, which is a converted garage. Mom has the doorbell with her. You can buy a medic alert system through walmart also.