Legal Question in Wills and Trusts in California

No, not with the information that you have provided. If he has left a valid will, he can designate anyone he wants in the will to receive his property. If he properly deeded property to her and placed her on title, you can't amend that. If the will is invalid or was forged, you would have to contest the will. If the deed was forged, you would have to sue to quiet title.

If you think there are any of these problems with either the deed or the will, you need to talk to an attorney familiar with probate law and real estate as soon as possible.