.
Allah declared all the wives our Prophet (SAW) Ummat ul momineen to declare them haram for anybody else after Prophet (SAW) to marry them.
Yes, otherwise we can not take the literal meanings of the word 'mother' here as my mother is mehram for me and i could touch her, hug her, travel with her, and so on but all this is out of question when it comes to the wives of the Prophet Peace b upon him and his purified family.
They are Mothers of the Believers for a believer will respect them like his/her own mother out of the respect of the Prophet pbuh&f.