This might work.

https://www.wayfair.com/Thomas-and-Betts-Carlon-Wired-Chrome-Bell-TBAC1072.html

Whatever you get, don't get a chime. You can't lean on a chime.

The style suggested by elltwo is pretty damn loud! We had something similar back in the day, but changed it out so we'd stop getting startled everytime the doorbell rang.

Or consider a wireless doorbell. That way she can put the "bell" unit in (or adjacent to) the part of the house she's in most often.

Some of the cheaper models don't get very loud, but that may not be an issue if enough if the base is in the same room as the listener. Reviews on-line will help identify the ones to weed out. We have had excellent service with a SadoTech.

Thanks everybody! The issue seems to have been resolved without me having to do anything, but I'll leave this thread here in case anybody in a similar situation needs to info.