Never. The only person in ivory should be the bride. It is inappropriate for a person at a wedding, mother or not, to wear the same color as the bride.
If the bride is wearing pink you should wear a different color as the bride is suppose to be the center of attention.
Anything she wants to.
Saree
Black.
The Mother of the Bride CAN wear black---but it would be very poor form. People at weddings should be wary of black.
The Maid of Honor should wear something different than the Bride in ANY wedding (trust me!)
the mother of the bride should wear red because it color coordinates well.
The mother of the bride should wear a color that corresponds with the wedding party, but not the same color, even if she is giving the bride away. She should not wear white or off-white, but she could wear the same color as the men's tuxedos.
No, it is not traditional for the mother of the bride to buy a nightgown and pajamas for the bride and groom. Sometimes the groom may wear just his underwear; just wear pajama bottoms or even be in the buff. The bride should pick out a nice negligee for her wedding night.
Father of the Bride
Unless you the parent of either the bride or groom or in the wedding party then no, you should not wear a flower on your dress.