From what I see given here, I'd say she's probably more at fault than your friend. (Of course, she doesn't seem to agree, and perhaps there's more to the story.)
Though if her problem is really just an out-of-true wheel, I'd probably say `look, this was your fault and not mine, but I can true a wheel in a few minutes. Stop by my place and I'll show you how it's done. We can also check out the rest of the bike to make sure everything is OK.' Especially if she's cute.
But I'd make really sure that she knows that I'm doing this to be nice, not because I (or my friend) are responsible. After all, she could decide that her knee was hurt and she wants a big cash settlement, and attempt to say that since I fixed her tire, I was admitting responsibility ...
I don't know if the actual laws are going to matter. The police are unlikely to give a ticket. If your friend has renters or homeowner's insurance, she could make a claim and they'd work it out. If not, and he denies responsibility, really, all she could do would be to sue him or take him to small claims court -- and then that's when the actual laws might matter. But usual cycling practice (announcing your passing, for example) may very well matter too.