Hello Zahedi,
1. ...we should go and see her more often. She is hinting, but it is us who should. Or "she hopes/insists that we would visit her'.
2, 1 D. ...so we didn't. or C ...so we haven't (gone). both are correct.
2, 2. a or b. ...But later that same day something strange occurred/ something strange took place (no "the") or something strange happened.
3, 1 A doctor rang/rung to tell us... Rang and Rung are both past tense of the word 'to ring'
2c she has gone into hospital.
4 a or b. We can't all go/ We may not all go ("may" gives the idea of permission, the doctors will not permit/allow ALL of us to go at the same time
5, 1 c got there
5 2 d seemed quite happy
5 3 b getting too old to drive
6c to take me. You take her from home to the beach.
You might want to bring flowers (to her). - to bring to her.