Is a system available for installation in our home which will allow us
to monitor the my 98 year old mother-in-law with sound and video. It
must be voice and/or motion activated and recorded on a remotely
located device which will permit recovery and review of sound as well
as video. Our objective is to monitor the performance of her full time
caregivers.

There are hundreds of internet sites marketing 'pinhole video cameras'
with built in transmitters.  The camera can be easily hidden, and it
transmits a video signal to a standard VCR elsewhere in the house.
These units are available for purchase for <$300. By using an 8-hour
video tape a good portion of her daily activities could be reviewed. 
I know of no off-the-shelf cameras that are motion activated.
It may be possible to rent this equipment for a few days from some
on-line companys, also.