inherently ambiguous means it's ambiguity cannot be removed
a)$L=L1 U L2={a^n b^n c^m}\cup {a^n b^m c^m}$
We can generate aabbcc,abc from L1 and L2 both
b)$L=L1UL2={a^n b^n c^m}\cup (a+b)^*$
But here L2 is regular grammer which deterministic. So, it is not inherently ambiguous grammer.
