At my husband's care home they have a commercial tape recording with snatches of the openings of songs (Daisy, Old Bull and Bush etc) and large boards with the titles of the songs which are covered as each song is played. In other words it is musical bingo.
Not sure what you could do with the lady who has bad eyesight but also photocopying some pages from colouring books and colouring them in seems to go down well.
Could you go to the library and find some books with pictures relating to a specific year or years, for example World War Two which would prompt them to talk about their own experiences during this period of history.
Simple chair excercises to music such as stretching, wiggling toes, waiving arms etc., are also good fun.
A large box of various old buttons to 'sort' and play with can also be a source of amusement.
If all else fails, suggest you all make a cup of tea together.
How lovely of you to do this for Help the Aged and very good luck to you. What people want more than anything is to be touched, chatted to and to feel wanted. If you can achieve this, you will have spent valuable time with them.
xxTinaT