In the old days women were solely responsible for looking after the house. Thus they weren't asked to attend funerals as they had to take care of the children and the house.
According to Hindu tradition,Â the men folk of the house go to the Shamshaan ghat or funeral pyre. Thus the women need to stay at home to clean the house and prepare the house for the guests as there used to be pooja and lunch.
The funeral is hard to watch. According to Hindu rituals the family members have to stay till the body is fully burn't. It can be a little traumatic and disturbing to watch the a family member's body decay in front. Women are therefore restricted from going there as sometimes they might be pregnant and this would have a traumatic effect on the baby.
The funeral is quite a horrible thing to watch. Sometimes the corpse jerks and has to be beaten to lay it back. There are foul and disgusting smells that comes off. Women are generally considered having a less brave heart. Thus they are refrained from watching this sight.
It is said that married women are allowed at the ghat. Whereas unmarried girls who are virgins have pure souls. It is easier for evil and wandering spirits to latch on to them. Thus women are forbidden to enter the ghat.
According to Hindu rituals,hair is a place from where evil spirits enter the body. Thus after a funeral men are made to shave their head to ward off all evil energy that they contract from the Shamshaan ghat. Women generally are not comfortable with shaving their hair. Thus they do not go to funerals.