there were multiple questions in there, so I will try to address them all in the order presented. If I miss anything or if more detail is needed, just let me know.
1. "If she does not live in their house would that be considered as legal separation
A. California is a no-fault divorce state, meaning that things like "abandonment" are mostly irrelevant to a party's property, custody, or support rights. However, for purposes of divorce or legal separation, the date of actual separation may impact their rights. The date of actual separation is different from the date of physical separation (although, they often coincide). Actual separation is when it is decided and communicated by one of the parties that the marriage has irretrievably broken down.
2. "Can he move out and take the children? "
A. Without a custody order in place, either parent of children can generally "move out" with the children, provided the other parent is not denied reasonable visitation with the children.
3. "Can he keep her out of the house?"
A. 99.9% of the time, the answer is going to be no in these situations; although you have given me no reason to believe that she falls under the 0.1% where the answer is "yes", I would need to do a full interview with her to say for absolute certainty. I hope that you understand.
4. "Can he make a "child visitation schedule " they are still married."
A. technically, the answer is "yes", but she can make one, you can make one, and a monkey with a pencil could probably make one. The point is that the schedule is not legally enforceable except by court order, which has not happened.
It is really important that a parent not be pushed around with regard to visitation earn on when problems arise; even though there is not a court order in place initially, it can set a precedent which the court will rely on when it does eventually get before the court. In other words, limited visitation without a court's order today can lead to limited visitation without a court's order tomorrow.
The court can order custody without starting a legal separation or divorce. I do not want any marriage to break down, but it is important that your daughter's rights be protected unless and until they can make their relationship functional again. Whether she gets an attorney or files for custody on her own, she needs to be proactive to protect her long-term rights.
I hope that this helps.