Seriously, stop and think for two seconds and you might stop regurgitating this vomit.
If there was a scandal, and Lois Lerner was involved, she will either (1) lie, (2) take the blame after getting immunity, or both. If there was no scandal, she will (3) tell the truth. However, without evidence other than Ms. Lerner's testimony (like her emails), it will be impossible to distinguish between (1) and (3). Thus, it would be beyond stupid to offer her immunity, because the only thing you would be doing is giving up the chance to prosecute her for something other than perjury if subsequent evidence is discovered that she was, in fact, lying.
Republicans aren't giving Ms. Lerner immunity because they want to avoid the truth. Rather, they have no reason to believe she will offer the truth.
Further, immunity is something you give to someone who agrees to provide evidence needed to land a bigger fish. It is not something you give to a person who refuse to identify bigger fish. It is also not something you give to someone who may actually be the biggest fish involved.