Taking dinner over is such a lovely idea...
Something handmade is lovely for family or friends esp if they dont need the $$
I know my mum wouldnt take money but a lovely card once in a while ans a gift i know she wants saying thanks for all you do for me goes a long way
pictures DS has done, sending her postcards from him etc
for a friend i think a voucher is lovely, also leave some nice food for her
and a handwritten note telling her how much it meant to you to go out would belovely