Possible Solution 1

Above is my first possible solution. It incorporates mortise lock with a hybrid electronic and analog key, an infra read beam and an electric motor powered door opening mechanism to open the door for the elderly person. 

Mortise Lock with Hybrid Key

The reason I have decided to have a hybrid key is that it will still give the elderly person the feeling of using a key, which they are accustomed to but gives them the added security of the electronic component which will prevent the lock from being picked.

Infra-red Beam

The infra-red beam detects when the elderly person has safely walked through the door and gives the opening/closing mechanism the signal to close behind the person.

Electric Motor Powered Door Opening/Closing Mechanism

The reason for there to be  an automatic door opening and closing mechanism is that it reduces the elderly person's physical strain while entering their house. It also prevents the elderly person from getting stuck outside of the house due to the door jamming.


Opinions

Good Points

1. Familiar to older people
2. The old person won’t have to think about closing the door
3. No effort for the person whatsoever

Bad Points

1. Expensive
2. Big ugly box on the door
3. A lot of installation as there are lots of peripherals

Things to think about

1. The concept is good but I think it could be made smaller and less obvious as older people like their houses looking good
2. The fact the mechanism (mortised lock) is familier to the old person will help him/her to adapt to the idea of the new door, Which is very important.