I agree with Ryoko-san. Let me add one more thing. ママis, in most time, used by children. You can use it for some reason, but you'd better call your mother おかあさんwhen you talk about it to your friend as well. ははおやis also widely used. It is formal but it could be casual too. What I'm trying to say is; おかあさん= casual. to your own mother and to your friend はは= formal. Used at an interview for a job or such. ははおや= sort of formal. Used at kind of formal situation. You can use it to your friend too.

In Japan, generally people call "mother" おかあさん or ママ when we talk to her but we say はは when we talk about our own mother with other people, especially in the formal situations. We don't use はは when we talk to our own mother. I hope you get the difference.

To add to above answers, おかあさん　is used to refer someone else's mother and/or your own mum at home. はは is used to refer only your own mother outside of your house.

はは = referring to your own mother おかあーさん = referring to someone else's mother, or addressing your own mother

Is it おかあーさん or おかあさん?