A, the reaction of sodium hydroxide and weak acid just generates a strong base and weak acid salt, and brine is alkaline, so we should choose the indicator that changes color under alkaline conditions instead of methyl orange, so we should choose phenolphthalein indicator, so A is wrong;

B, the end point of the reaction means that the acid-base has just completely reacted, and the indicator is a color change range, so B is wrong;

C, when the acidity of the acid is very strong and the concentration is diluted, the mutation range increases, and the size of the mutation range is related to the strength and concentration of the acid, so c is correct;

D, acid burette with piston can't hold sodium hydroxide solution, and sodium hydroxide solution is held in alkaline burette during titration, so D is wrong;

So choose C.