Public transport: Perhaps, the most efficient way of getting to BC's math department (Carney Hall) and the conference venue (McGuinn Hall) is Green Line D. Get off at the Chestnut Hill T stop and walk for about 0.6 miles. The whole trip from the Holiday Inn Brookline should take about 32 minutes. Here are the precise directions. It is also possible to get off at the Reservoir T stop and take the BC shuttle to the campus. See below.
There are two alternatives to the above directions: The first is to take Green Line C (the train stops right in front of the hotel) to the Cleveland Circle (10-12 minutes) and walk 1.2 miles (25 minutes) around a picturesque reservoir. Instead of walking, you can also take a free BC shuttle from the Reservoir T stop or the Chestnut Hill Ave stop (weekend schedule in pdf). During the week, shuttle runs every 10-15 minutes. The weekend frequency is every 30 minutes in the morning, every 15 minutes in the afternoon, and every 10 minutes in the evening. The first shuttle departs Reservoir T station at 8am. Real-time shuttle location can be seen here.
The last alternative is to take Green Line B to the Boston College stop. Although this alternative requires the least walking, there is a long flight of stairs and Green Line B is the slowest tram line in the whole Boston Metropolitan area if not the whole Northeast.
Taxi: The McGuinn Hall is 3.0 miles west from the Holiday Inn. The cab fare from the hotel will cost $11 without a tip.
Driving: Visitor's parking is available next to the conference venue at the Beacon Street Garage near the intersection of Beacon and Chestnut Hill Drive, Boston, MA 02135. The fee-per-exit is $5. The entrance to the Beacon Street Garage is just a few blocks headed west on Beacon Street from the Chestnut Hill Drive. There is also metered street parking along Beacon Street (3 hour limit, free after 6pm and on Sunday), which can be limited during Friday afternoon.