Yes, you can object to the requested discovery as irrelevant, overly broad and abusive. Those are standard objections and certainly the rule of thumb is that anything over 10 years is too far back.
You can try to answer limitedly, which begs a contempt motion in response. Or you can file an objection/protective order to the discovery. You could also attempt to talk to the attorneys and ask what exactly they are looking for and attempt to come to an agreement. The last is effective but dangerous as a pro se, since your statements are directly admissible as evidence.
Upshot is that you should talk to an attorney for specific advice. You didn't mention how much they are looking for but your exposure is at least that much, potentially more if they are asking for interest.