The table below shows lots of ways of looking out for those you care about each with their strengths and weaknesses. For instance though Canary Care is the most expensive it is suitable for people who could not consciously interact and so may be suited to more advanced needs.
At the other end of the spectrum wellbeing calls can be very cheap but do they give you enough information? Once a day you know someone is responsive, provided they are able to answer the phone.
The Disabled Living Foundation has a comprehensive explanation of all the choices here
Numbers in brackets have explanations below the table of features.