c
(c) $f$ is continuous at $x = 0$, $f({0^ - }) = f({0^ + }) = f(0) = - 1$
Also $Lf'(0) = Rf'(0)$
==> $\mathop {\lim }\limits_{h \to 0} \frac{{f(0 - h) - f(0)}}{{ - h}} = \mathop {\lim }\limits_{h \to 0} \frac{{f(0 + h) - f(0)}}{h}$
==> $\mathop {\lim }\limits_{h \to 0} \left( {\frac{{{e^{ - 2h}} - 1 + 1}}{{ - h}}} \right) = \mathop {\lim }\limits_{h \to 0} \left( {\frac{{ah + \frac{{b{h^2}}}{2} - 1 + 1}}{h}} \right)$
==> $\mathop {\lim }\limits_{h \to 0} \left( {\frac{{ - 2{e^{ - 2h}}}}{{ - 1}}} \right) = \mathop {\lim }\limits_{h \to 0} \left( {a + \frac{{bh}}{2}} \right)$
==> $2 = a + 0$ ==> $a = 2,\,\,b$ any number.