Manava Dharmashastra 5.146

5.146

tathā coktam"tatsapiṇḍeṣu vā satsu pitṛpakṣe prabhuḥ striyāḥ | pakṣadvayāvasāne tu rājā bhartā striyā mataḥ ||" tatsapiṇḍeṣvityādinā cāsatisvāmini kartavyam |

Medhātithi’s commentary (manubhāṣya):
It has been declared thus—‘In the absence of any sapiṇḍa-relation of her husband, some one on her father’s side shall be the woman’s protector; on the total extinction of both families, the King has been declared to be the woman’s guardian.’

This refers to a case where the husband is no more. (146).