If the tenant fails to timely respond to the complaint, you can file for a default and clerk's judgment. You can find useful forms at
If the defendant fails to respond to the summons & complaint, you may submit a request for entry of default (Judicial Council for CIV-100). And then, once default has been entered, you may submit your request for default judgment (see California Code of Civil Procedure Section 585(d)).
It is not clear whether the complaint for unlawful detainer names the correct plaintiff. Is the landlord your father? Or both your mother and father as individuals?
If the landlord is an entity such as a corporation, LLC or limited partnership, it must be represented by counsel in order to participate in litigation.
Frank W. Chen has been licensed to practice law in California since 1988. The information presented here is general in nature and is not intended, nor should be construed, as legal advice for a particular case. This Avvo.com posting does not create any attorney-client relationship with the author. For specific advice about your particular situation, please consult with your own attorney.