Those 2 addresses have Vanessa spelled with 2 Ns, unlike what the OP posted. Plus, I doubt a new address would show up on the internet in one month's time. And names of underage children will not
show up on a people-search. Nothing shows up using Vanessa's name and birthdate. Could she be using a different surname? (married or maiden name)
If she was working, her mother could try going to her workplace. If she was receiving assistance for the children, her mother can try to get a message to her through her case worker. Look here for phone numbers.
Department of Human Services Internet
If she has the children with her and is receiving assistance, she's probably still in San Bernardino County. ( Those 2 addresses are in Los Angeles County and Orange County).
She's might be staying with a friend, so her mother could try contacting her friends and get a message to her that way. Something along the lines of, "I'm sorry, I'm worried about you, please come home or call me." Anything to break the ice and re-establish contact.