The correct option is
B Ms.Pratibha Devisingh Patil, the President of India, is the first lady to hold the post.
The word, 'Ms.' is the abbreviation of the word, 'Miss' and is used as title for women. The first letter 'M' has to be capitalised and then the word itself should be followed by a dot. 'Ms.' (with a dot) is the correct representation. In option D, the word, 'Ms' is followed by a comma and not a dot. This is incorrect.
The word, 'Prathibha Devisingh Patil' is a proper name of a lady. The first letters of all the words i.e 'P', 'D' and 'P' have to be capitalised. This is correctly followed in options A and B. In option C, the letters 'd' and 'p' are not capitalised. In option D, the letter 's' has been incorrectly capitalised.
The word, 'President' is a title for the head of a country. The first letter 'p' has to be capitalised, especially when the name of the President is used in the same sentence. In options A, C and D, this rule is not followed.
The word, 'India' is a proper noun referring to the name of a person. Hence, the first letter 'I' has to be capitalised. In options C and D, this rule is not followed.
As there are errors in punctuation in options A, C and D as explained above, these options are incorrect.
The only option which follows all the above-said punctuation rules in option B. Hence, this is the correct answer.