Almost any of the security cameras available from Amazon, B&H, NewEgg and others includes a web service. Internet access (wifi) is normally needed wherever the camera is located.
Do you relatives really want to be monitored? My 98-year-old mother in law would never speak to us again if we installed a camera in her house. Plus, you’d need to monitor every place in the house – including intrusive areas. An medical alert system might be more appropriate, and could summon emergency help when needed.