If I was defending your father I would like his chances.
The response above is not intended as legal advice since it’s impracticable to provide thorough, accurate advice based upon the query without additional details. It is highly recommended that one should seek advice from a criminal defense attorney licensed in your jurisdiction by setting up a confidential meeting. Moreover, this response does not constitute the creation of an attorney-client relationship since this message is not a confidential communication because it was posted on a public website, thereby publicly disclosing the information, which is another reason to setup a confidential meeting with an attorney.
Your question lacks the factual predicate required to give a "yes" or "no" answer. Suffocating someone with a pillow CAN be charged as attempted murder. However, it is incumbent upon the State to prove the elements of the charge (including the mens rea--intent-- of the defendant).
Your question suggests that the even occurred some time ago, making proof even harder (memories fade, evidence dissipates). Further, depending on how long ago the events occurred, your potential civil claims may be barred by the applicable statute of limitations.
Consult with a local attorney to determine the viability of any potential course of action.
There is not enough information here form an intelligent speculation.
The above is not intended as legal advice. The response does not constitute the creation of an attorney client relationship as this forum does not provide for a confidential communication.