What is the best type of bed for parents that still sleep together that is before you get a hospital type of bed?

doubledement, I am not really sure what you are questioning.

If your parents are use to a king size bed, then keep the king size bed. Anything smaller may feel uncomfortable.

Do they need one that adjusts to sit up ?

I would recommend a sleep number that is adjustable.

Each side operates independently for optimum comfort for both.