Does a plaintiff need to go out of county for a deposition, 79 miles away from their residence and scene of the accident for convenience of defense

There are actually 2 potential locations for a deposition in California, both of which are at the option of the party noticing the deposition.  The first location is within 75 miles of the deponent's residence.  However, the second is within the county where the action is pending - and - within 150 miles of the deponent's residence.  (Code Civil Procedure section 2025.250(a).)  Is the action pending in Contra Costa County?  If it is, then the deposition location is ok as it has been noticed.  If the action is pending anywhere other than Contra Costa County, then the defense is exceeding the 75-mile cap, and you should object.  If you object, you are objecting to the deposition notice so the governing statute is Code Civil Procedure section 2025.410, which states that the objection should be raised "promptly" and "at least three calendar days" prior to the date of the deposition.  Be mindful that the 3 calendar days is extended by means of service; e.g., +5 for service of objections by mail.  You can probably find a sample objection at the Sacramento County Law Library, which has one of the best law libraries anywhere in the state, especially for self-represented litigants.  Having said that, you really should have an attorney assisting you, even if it's on a limited basis.  This sort of forum is not suitable for someone already involved in litigation and does not take the place of having an attorney on your side.  There are a lot of pitfalls for the unwary in the Code of Civil Procedure, and the defense is sure to make the best of all of them.  I handle cases in the East Bay (my office is in Santa Rosa).  Where is your case filed, and how small is it?  Feel free to email me.