Bismillah-hir-Rahman-nir-Raheem
Assalamu-`alaykum wa rahamatullahi
wa barakatuhu
Rasulullah (Sallallaahu
Álayhi Wasallam) said that someone should lend her a veil[jilbab]
Sahih Al-Bukhari Volume 1, Book 8,
Hadith # 347
Narrated Um 'Atiya (Radhiallaahu Ánha) We were ordered (by Rasulullah '(Sallallaahu Álayhi Wasallam) to bring out our menstruating women and veiled women in the religious gatherings and invocation of Muslims on the two 'Eid festivals. These menstruating women were to keep away from their Musalla. A woman asked, "O Allah's Apostle ' What about one who does not have a veil (the veil is the complete cover with only one eye or two eyes showing)?" He said, "Let her share the veil[jilbab] of her companion."
Allah knows best.