My Dad Is 89 Years Old,He Was Prescribed This Medication

my dad is 89 years old,He was prescribed this medication for constant urinenation? or having to urinate alot so he says,keeping in same my dad is 89 and has nooooo patience and was drinking alot of soda with caffiene ,6 years ago he was prescribed flomax because he could not urinate.So im very concerned the dr. only prescribed 30 pills once a day and now im worried,When these pills are gone and he starts to p more then trhee times a day give or take what then whats the normal i am 57 and i go (urinate) i guess 4 or5 x a day depending on how much fluid i drink.what do you think about my dads situaion.