Paul Walker -- Asked Mom To Care for Meadow the Day He Died

Just hours before he died in a fiery car crash, Paul Walker told his mother he was too busy to properly care for his teenage daughter ... and asked her to become the girl's legal guardian ... TMZ has learned.

Sources close to the Walker family tell us ... Paul approached his mother, Cheryl, on November 30th and asked her to retire from her nursing job to take care of Meadow full-time.

Turns out Walker had been overwhelmed with his work schedule and couldn't juggle that with his parental responsibilities. So in August -- 3 months before he died -- Meadow moved in with Cheryl, who was working full time.

Paul hired a series of nannies to care for Meadow when Cheryl was on the job, but none of them worked out.

So finally ... on the morning of his death, Paul called Cheryl and said he had given up on the nanny search and wanted her to be a full-time, stay-at-home grandma. Cheryl agreed, and Paul then called other family members to inform them of his decision.

As we previously reported ... Meadow's biological mom has a serious drinking problem and Paul never considered her an option. Meadow had been living with her mom until 2011, when she moved in with Paul.

Cheryl has now filed formal papers to make her Meadow's legal guardian.