and her admirable desire to care for him, what alternative life could she have?

She already is involved with charitable endeavours locally ,and has no desire to extend these in any patronising manner.

There is no one else to "pal " up with apart from Harriet (Mrs Weston is busy with her own family concerns, Jane Fairfax is cool to approaches) , with whom to explore interesting things/ ideas. And Emma can't travel away from Highbury to do them either, by visiting Isabella and John often in London because of Mr Woodhouse

Sadly,it also seems to me that Emma has few inner resources: she abandons well thought out and improving reading lists and doesn't practise the piano enough, she also does not like to walk alone.